The Black Crag Route

I had been driving Scottish Environment Protection Agency vehicles for ten years when I became involved in the Strathgarve business. Most of that time was spent working alone on back roads, the sort of routes where you might see three other vehicles all day if you were lucky. That suited me. I tested private boreholes, took soil samples, completed chain-of-custody forms and drove back. Simple and quiet.

It was the kind of job in which you learnt every stopping place between Inverness and Fort William and stopped being surprised by how many shades of green a Highland forest could turn. It stayed that way for a long time. Routine work. A farmer worried about run-off from a neighbouring field. A householder who suspected the previous owner had buried something he should not have.

Once in a while, I found genuine contamination and the case went upstairs, but most of it was peace-of-mind work. Prove the water was clean, log the result and move on. I assumed it would continue that way until I retired or my knees gave out, whichever came first.

October changed that.

Fiona Mercer called me into her office on the afternoon of 14 October. She had the look she wore when she had already made a decision and the conversation was only a formality.

Her desk was clear apart from an open folder and a mug printed with WORLD'S OKAYEST BOSS. I was fairly sure somebody had given it to her as a joke and she had kept it because she had not understood the joke.

"Strathgarve," she said, without waiting for me to sit down. "We've had complaints about a metallic taste in private borehole supplies near Loch Garve Reservoir. Three properties, all within a two-mile radius."

I took out my field notebook. "Any recent drilling in the area? Mining activity?"

"Nothing active. Forestry and Land Scotland says the old workings have been quiet for years." She slid the folder across the desk. "It's probably nothing. Seasonal mineral leaching, perhaps, or a corroded pressure vessel somebody forgot to replace. But we need it documented."

"How many sites?"

"The three complainant boreholes, plus the five follow-up monitoring points already authorised in the file. Standard dissolved-metals analysis at each. I want it closed out by next week."

That was Fiona. Everything had a deadline, and the deadline was always yesterday.

I went through the file. The complaints had arrived during the previous month, all referred by Highland Council Environmental Health before reaching us. Standard procedure. Nothing in the notes appeared unusual. Just three people saying their water tasted wrong.

"When do you want me there?"

"Tomorrow. I've already booked you a room in Inverness."

She turned back to her computer. That was it. Meeting over.

I took the folder and left. Fiona treated every assignment the same way. It did not matter whether it was a major industrial site or somebody's odd-tasting tap water. Close it quickly. File the report. Move on.

I understood. We were always short-staffed, and there was always more work than time. Even so, I sometimes wondered whether she cared what we found or only that the paperwork was finished. Probably both. That was the job.

I drove home, put some clothes into a holdall and checked my field kit twice. Then I checked it again, because that was what you did. In ten years I had learnt that the assignments which looked simplest on paper were precisely the ones on which you forgot something stupid: a spare battery, the correct adaptor, a calibration solution. Once, I had driven four hours before realising my calibration standard was still on the kitchen worktop. I had been forced to turn round and begin again the following morning.

Fiona had enjoyed that. I did not make the same mistake twice.

The Premier Inn stood beside the A9 on the outskirts of Inverness, not far from Cotswold Outdoor. I had stayed there perhaps a dozen times. They knew the SEPA rate, did not ask questions and provided tolerable coffee in the lobby at five in the morning. That was all I needed.

I checked in at about 19:00 on 14 October. The man at reception barely looked up from his mobile. He pushed a key card across the counter and pointed towards the lift.

Room 214. The same floor as usual.

The room smelt of industrial carpet cleaner and artificial lavender. It had two double beds, a desk fixed to the wall and a television I did not switch on. I dropped my holdall on the bed nearest the door and laid my equipment across the other one.

Field kit. Sample bottles. Labels. Cooler. Chain-of-custody forms. GPS unit. Backup GPS unit. Laminated maps. Mobile charger. Backup charger. First-aid kit. A red emergency beacon flare in the vehicle incident kit. Water. Oat bars.

I worked through the inventory as I always did, checking every item against the list in my head. Everything was there.

I labelled the sample bottles in advance. I had begun doing that several years earlier. It saved time in the field and meant I did not have to attempt legible writing with cold hands in somebody's muddy garden.

The file covered three complainant boreholes and five pre-authorised follow-up monitoring points. Three bottles per site made twenty-four, and I prepared three more labels in case conditions justified adding the Allt Ruadh surface-water site. Twenty-seven bottles altogether. I carried spares as well. You never knew when you might need to repeat a sample.

The chain-of-custody forms went into a plastic sleeve. I completed the header with my name, Fiona's case number and the fieldwork date, 15 October. I left the sample identifiers and collection times blank. Those had to be entered at the site.

That was procedure, and I did not interfere with procedure.

I set alarms for 04:30 on both phones and on a small battery alarm clock. It was probably excessive, but I had slept through a phone alarm exactly once. Once had been enough.

Then I sat on the edge of the bed and studied the maps.

Strathgarve lay south-west of Inverness, reached by the A82 and a connecting Highland A-road, tucked between the Monadhliath foothills and the Great Glen where Garve Forest began to thicken. Loch Garve Reservoir lay just beyond the village, holding back part of the River Garve. The three complainant properties were spread along the northern shore, reached by Forestry and Land Scotland roads that changed from tarmac to gravel and then to dirt the farther you went.

It looked straightforward. Drive out, knock on doors, collect the samples and drive back. Four hours of work, perhaps five if people wanted to talk. I would be back in Inverness by early afternoon and finished before dinner.

That was the plan.

I went to bed at about 21:00 and slept badly. I always did before field days. My mind kept repeating the checklist. Bottles labelled. Cooler packed. GPS charged. Forms ready.

It was like counting sheep, except the sheep were sample containers, and if you miscounted one you had to explain yourself to Fiona.

The alarms sounded at 04:30. I was already awake. I collected a coffee from the lobby on my way out. It tasted like burnt water, but it was hot and free, and that was enough.

The vehicle stood where I had left it in the car park: a white, high-mileage Land Rover Defender with SEPA markings on the doors and enough salt staining the paint to obscure the telephone number beneath. I had driven that particular Defender for three years.

The heater squealed when switched on. The passenger mirror was cracked, and the odometer had passed 187,000 miles during the spring. But it started every time and had good tyres. That was what mattered.

I loaded the coolers into the rear compartment, secured them with straps and checked the fastenings twice. Then I left the car park and headed south-west.

The A82 ran through the Great Glen before the connecting road turned towards the Monadhliath foothills. In October, before dawn, there was little traffic. A few timber lorries, perhaps, and some early commuters nearer Inverness. Farther out, there was only the road and dense ranks of spruce and pine pressing in from both sides.

It was raining. Not heavily, just the constant Highland drizzle that turned the world grey and made the carriageway shine like oil. I kept the wipers on intermittent and used full beam where the road allowed. I did not see another car for the first twenty minutes.

I passed the Garve Forest district office shortly before 06:00. Lights shone inside, but the car park was empty. Too early even for Forestry and Land Scotland. The building stood back from the road, a low brown structure that looked like every public office built in the 1970s. I had stopped there several times over the years, usually to arrange access through locked gates or check which forestry operations I needed to avoid.

The staff were competent and professional. They kept to their work and I kept to mine.

Beyond the district office, the road began climbing. The plantations grew denser and the drizzle became proper rain. When the clouds lifted, I could see the hills, dark and broken, with a little early snow caught on their northern faces. It might have been beautiful. I was mostly watching the road.

The coolers rattled whenever I struck a pothole. I could hear them over the engine and rain. I had packed them with frozen blocks, double-bagged to prevent meltwater reaching the samples. Standard procedure. Samples had to remain chilled from collection to delivery or the laboratory could reject them and I would have to repeat the entire trip.

I did not want to repeat it.

About ten miles beyond the district office, I pulled into a lay-by and checked the GPS against my paper map. It was an old habit. The GPS was probably correct, but paper did not run out of power or lose its signal beneath thick tree cover.

The three properties were marked in pen. I had done that the previous evening. They lay on the north shore of Loch Garve Reservoir, approached by Forestry Road 12 and smaller spurs with names rather than numbers: Muirside Lane and Burnside Track. They were the kind of roads that had probably begun as somebody's drive before a sign made them sound more important.

Everything matched. The GPS put the first property about fifteen minutes away. I pulled back onto the road.

Strathgarve emerged from the rain at about 06:30. It was a small forestry village of perhaps three thousand people, built around timber work that mostly no longer existed. There was one main street, with a fish-and-chip shop, a hardware shop and two pubs that opened too early and closed too late. I had passed through a dozen places like it.

They all had the same look: tired, but holding on.

I did not stop. My sites lay beyond the village, nearer the reservoir. I turned onto Loch Garve Road, where the surface deteriorated into patches, cracks and stretches where the tarmac had surrendered to gravel. The rain fell harder. The wipers struggled to keep up.

Forestry Road 12 branched to the right. It was gravel, as expected. The Defender coped easily, but I slowed regardless. There was no point arriving with damaged suspension because I had been in a hurry.

The first property was a mile and a half along on the left. I watched the odometer and the treeline. There were few houses. Those I passed stood well back from the road, mostly ageing prefabricated homes with LPG tanks in the gardens and vehicles supported on axle stands.

Working-class homes and holiday properties. The sort of place people visited at weekends to escape the city, or the sort of place they ended up when they could no longer afford anywhere else.

I slowed as the mileage approached the figure in my notes and found the entrance. There was no name on the post, only the number 3472, matching the file.

I parked beside a shed that appeared to be holding itself upright out of spite. The house was a single-storey prefabricated building with a covered porch and a satellite dish strapped to the roof. Lights were on. Somebody was awake.

I took my clipboard and stepped out. The rain struck at once, cold and spiteful. I pulled my SEPA jacket closed and walked towards the porch. Before I could knock, the door opened.

"You the environmental officer?"

The man was in his sixties, with a grey beard, a checked work shirt and suspicious eyes.

"Martin Shaw, Scottish Environment Protection Agency." I held up my identification. "You contacted Environmental Health about your borehole water."

He examined the card, then me, then the card again.

"Took you long enough."

"Yes, sir. I'm here to collect samples. It shouldn't take more than twenty minutes."

He grunted and stepped outside. "Borehole's round the back. Pump house is unlocked."

I followed him through the rain to a timber hut behind the house. He opened the door and pointed to the pressure vessel and the mass of pipes rising through the floor.

"Tastes like I'm sucking an old copper coin," he said. "Started about a month ago. Thought it would go away, but it hasn't."

"Has anyone else on the property noticed it?"

"Just me. My wife can't taste it, but her sense of smell's been ruined since she had Covid."

I took out my bottles and began work. There was a sampling tap immediately beyond the pressure vessel. I allowed it to run for two minutes to flush the line, then filled the bottles one by one, checked their labels and recorded the collection time. The man stood in the doorway watching.

"Do you think it's safe?" he asked.

"I can't say until we have the laboratory results. If you're concerned, use bottled water for drinking until we know."

"Already am."

I sealed the final bottle and placed all three in the field cooler.

"We should have results in about a week. Someone from Highland Council Environmental Health will contact you."

He nodded. He did not thank me. He simply returned to the house and closed the door.

I loaded the cooler into the Defender and checked my schedule. Seven more authorised monitoring locations remained, along with the possible surface-water site at Allt Ruadh. The next monitoring borehole lay three miles south on a spur that did not appear maintained. I decided to take that one next and work outwards before looping back towards the village.

That was the plan.

I left the drive and continued deeper into the forest. The wipers beat steadily, the coolers rattled behind me and every bottle was labelled and logged precisely as it should be. A simple assignment. Routine work. Close it out and move on.

The feeling in my stomach suggested otherwise, but I ignored it.

That was what you did. You followed procedure. You collected the samples. You let the laboratory tell you whether there was a problem.

That was the job.

I kept driving.

By late morning, I needed ice. I had completed several of the follow-up sites, but there were still more to visit, which meant another four or five hours in the field. The frozen blocks would only hold their temperature for so long. I was also running low on nitrile gloves. I had packed twenty pairs and already used eight because I kept double-gloving when handling the bottles.

Probably excessive. That was me.

The local Co-op Food stood at the northern end of Strathgarve's main street, opposite a closed petrol station and a cafe whose sign looked unchanged since the 1980s. The car park was nearly empty: one rusting Subaru and a Toyota pick-up with a cracked windscreen.

I pulled in at about 11:30 and took my wallet from the centre console.

Inside, the shop smelt of bleach and old vegetables. Fluorescent lights hummed overhead. The aisles were narrow and several shelves were only half stocked. At the back, I found two 5 kg bags of ice behind the misted glass of a freezer cabinet.

I carried them to the front, looking for gloves as I went, but saw none. I decided to ask at the till. Only one was open.

The man working it looked to be in his mid-twenties. He had black hair and wore a Co-op polo shirt one size too large. His name badge read CALLUM.

He was looking at his mobile when I approached, but put it away quickly and scanned the ice.

"Need a bag?"

"I'm all right."

He nodded and totalled the purchase. It came to a little over seventeen pounds. I took out my card. That was when he noticed my jacket and the SEPA emblem on the chest, the same emblem worn on every field jacket I had been issued in ten years.

"You with the government?"

"SEPA."

He paused, watching me for a second longer than seemed natural.

"So you deal with water and pollution and that?"

"Boreholes, rivers, soil contamination. It depends on the assignment."

"Do you deal with missing people?"

I stared at him. "No. That's a police matter."

He tapped a knuckle against the counter. He had not handed me the receipt.

"But you take calls, don't you? You've got a hotline and all that."

"We have a contact line for environmental incidents."

I waited.

"Three weeks ago," he said. His voice tightened. "I called about water quality because I didn't know who else to try. The police weren't doing anything. They said there wasn't evidence of a crime. I thought if I reported an environmental problem, somebody might actually come out."

I said nothing. I let him continue.

"My sister's missing."

He said it flatly, without preparation.

"Isla. She's seventeen. She disappeared after a bonfire on Allt Ruadh Road on 19 September. Just gone. No phone, no messages, nothing."

"I'm sorry."

"She's not the only one."

He took out his mobile and unlocked it with his thumb.

"Three others since spring. All young people, all from round here. Police Scotland says some may have left voluntarily. Says young people leave small places all the time, and there isn't evidence of foul play."

I glanced towards the entrance. There was nobody else in the shop, only the two of us, the hum of the freezers and the ice melting slowly on the counter.

"I'm genuinely sorry," I said. "But I don't handle missing-person enquiries. You need to keep pressing the local station, or ask whether the cases can be reviewed by specialist officers if there's evidence linking them."

"I know." He cut across me, not angrily, only wearily. "I know you don't investigate missing people. But you're here. You actually showed up. Nobody else has."

That troubled me. I had not shown up for him. I had come for borehole samples and a metallic taste complaint. I did not correct him.

He turned the mobile towards me. The photograph showed what looked like a route sign, although it was not official. Someone had painted a symbol on a piece of plywood, or perhaps directly on a post: a broken ring bisected by a downward-pointing chevron. The white paint was uneven, and the picture had been taken at night with a flash.

"This was near where Isla disappeared," Callum said. "Allt Ruadh Road, perhaps four hundred metres beyond the turning for the campsite. I found it two days after she vanished. Took the picture and showed Police Constable Drummond. She said it was probably some young person's art project or a route marker."

I studied it.

It resembled no Forestry and Land Scotland marker I had ever seen. Their signs used standard colours, lettering and pictograms. This was crude and deliberate, but not professional.

"Have you ever seen anything like it?" he asked.

"No."

"Neither have I, and I've lived here all my life."

I should have paid and left. I should have told him I had a job to finish and that he needed to continue through the proper channels. But something in his expression stopped me. Desperation, perhaps, or simply the knowledge that he had tried an environmental hotline because he had exhausted every other idea.

I took a pen from my jacket pocket, picked up the receipt he still had not given me and turned it over.

"Describe the symbol again."

He did. I sketched it: a broken ring, bisected by a chevron pointing down. Simple enough.

"Where exactly on Allt Ruadh Road?"

"Past the campsite turning. Four hundred metres, perhaps a little more. There's a lay-by on the left with an old fire ring. The sign's just beyond it, on the right, nailed to a tree."

I wrote that down as well: Allt Ruadh Road, beyond campsite, right-hand tree.

"When did the other three disappear?"

"The first was in April. Jamie Kerr, nineteen. He worked at the hardware shop. Then Megan Pritchard, sixteen, on 23 June. The third was on 17 August. A man of twenty-one called Rhys. I don't know his surname. I didn't know him well."

I wrote the names: Jamie Kerr. Megan Pritchard. Rhys, surname unknown.

Then I stopped and looked at him.

"Did you tell the police about all four together? About the possible pattern?"

"Yes. Constable Drummond took my statement. Said there wasn't enough to establish a link. Said Isla might have got a lift to Inverness or Glasgow and might come home when she ran out of money."

"Do you believe that?"

"No." The answer was immediate and certain. "Isla didn't run away. She was working on her university applications. She'd arranged seasonal work at the fish-and-chip shop for the Christmas holiday. She wasn't going anywhere."

I folded the receipt and placed it in my chest pocket with the pen.

"I can't investigate this. It isn't my role. But I'll keep my eyes open while I'm working in the area. If I see anything connected with the environmental complaints or the access roads, I'll record it."

It was not a promise. I made certain of that. But it was something.

Callum nodded and handed me the card receipt at last.

"Thanks."

I collected the ice and left.

I did not drive directly to my next authorised monitoring point. I should have. I still had several locations on my list before I could return to Inverness, hand the samples to the approved courier and finish the day's paperwork. But Allt Ruadh Road was only a few miles away, and one of the monitoring points lay farther east.

It would cost me no more than twenty minutes to pass the place and look.

That was what I told myself.

I drove south with the ice in the passenger footwell and Callum's receipt folded into my chest pocket. The rain had eased, but the road remained slick. I passed the district office again and continued for another three miles until I saw the sign for Allt Ruadh Road.

It was a narrow gravel turning with trees pressing close on both sides. The campsite entrance appeared on the left after about half a mile. It was closed for the season, with a chain across the access road and a wooden sign reading NO SERVICES AFTER OCTOBER.

I continued. Another four hundred metres brought me to the lay-by Callum had described. An old fire ring lay in the middle, surrounded by charred logs and lager cans half hidden in the weeds.

I slowed and looked to the right. It took a moment, but I found it.

A sign was nailed to a spruce at chest height. The same symbol shown in the photograph: a broken ring bisected by a downward-pointing chevron. The white paint had begun to peel, but the design remained clear.

I pulled over, got out and approached the tree.

The paint was cheap, perhaps ordinary exterior emulsion, applied by hand. The timber beneath it was fresh. The sign had been put there recently, no more than a few months earlier.

It made no sense as a route marker. The location was wrong, the style was wrong and it pointed towards nothing I could see. Only one tree among thousands.

I photographed it with my mobile. Then I returned to the Defender, collected the GPS from the dashboard and recorded the position as 57.15684, -4.71263.

I stood beside the vehicle for a while, trying to decide what I was doing. Missing young people and strange signs were not environmental complaints. But I had told Callum I would keep my eyes open, and that was what I had done.

I got back into the Defender and continued.

I spent the rest of the afternoon on my actual assignment. The Allt Ruadh surface-water site could be reached by another forestry spur about a mile east. Because it lay within the same drainage area as the authorised monitoring points, I used the contingency labels and added it to the sampling run.

I parked near a footbridge and walked down to the burn carrying my field kit and handheld meter. Allt Ruadh was high after the rain. I measured temperature, pH, dissolved oxygen and conductivity. Every reading was normal. I filled three bottles anyway, because that was procedure, recorded the time and coordinates, and packed them in the cooler with fresh ice.

After that I continued through the five authorised SEPA groundwater monitoring boreholes and the remaining two complainant properties, some near the connecting A-road and others reached by rough forestry spurs. The routine never changed.

Knock. Show identification. Explain that I was there to test the water. Flush the sampling point. Fill three bottles. Check the labels. Record the time.

One man asked whether his water was safe. I gave him the same answer I had given Martin Shaw's first caller.

"I can't say until the laboratory completes the analysis. Use bottled water if you're concerned."

Nobody thanked me. That was fine.

By 16:30, I had completed all nine sites: three complainant boreholes, five pre-authorised groundwater monitoring boreholes and Allt Ruadh. Twenty-seven sealed bottles sat packed in ice. The chain-of-custody forms were complete. GPS coordinates were logged for every collection point.

I sat in the Defender and reviewed my notes again. Everything appeared correct.

I could return to Inverness, secure the samples in the approved collection refrigerator before the courier cut-off, file my preliminary report and finish for the day.

But something continued to nag at me.

I unfolded the map across the steering wheel and marked each sampling point with my pen. Three private boreholes lay along the northern shore of Loch Garve Reservoir. The five monitoring points spread east and south along the forestry routes. Allt Ruadh lay on the southern edge of the same area.

The sites did not form a straight line, but they were not randomly scattered either. All nine fell within roughly five miles, and each was near a Forestry and Land Scotland road or access point.

Boreholes could share groundwater bodies. That was normal. If one source became contaminated, neighbouring supplies in the same zone might show similar effects. But this felt different.

The three complaints had all arrived during the previous month and described the same metallic taste, yet the boreholes were far enough apart that they should not necessarily have drawn from an identical local source. I traced the roads with one finger. Forestry Road 12 connected most of the sites, directly or by smaller spurs. Other tracks branched towards the reservoir and Allt Ruadh.

Old timber routes, perhaps, or access to former workings.

Mining.

Fiona had mentioned inactive claims, saying Forestry and Land Scotland believed they had been quiet for years. Quiet did not mean harmless. Nor did it mean nobody was using the roads.

I folded the map and started the engine.

It was probably nothing more than ageing borehole fittings and mineral-rich groundwater. The laboratory would tell me whether I was wrong. Even so, I kept thinking about the painted symbol, Callum's missing sister and the three others who had vanished since spring.

I began driving back towards Inverness with the coolers secured behind me and twenty-seven bottles that would probably come back clean.

What I needed was gate access.

That was the trouble with forestry roads. Many were locked after the main season, and others required a combination or prior authorisation. If the results required follow-up work, I did not want to telephone the district office every time I reached a barrier. I needed the codes entered properly against my SEPA access authority.

The Garve Forest district office stood two miles outside Strathgarve, the same low, single-storey building I had passed earlier. Three vehicles occupied the car park when I arrived at about 17:15. The daylight had already turned grey, and rain was still falling.

I took my clipboard and went inside.

The building smelt of coffee and wet carpet. A woman at the reception desk looked up. She was in her mid-fifties and wore reading glasses on a chain.

"Can I help you?"

I showed her my SEPA identification.

"Martin Shaw. I'm dealing with a water-supply complaint around Loch Garve Reservoir and Allt Ruadh. I need access information for several gated spurs in case follow-up samples are required."

She nodded without asking further questions.

"You'll want Alastair. He's got the access maps."

She lifted the desk telephone, pressed three numbers, spoke too quietly for me to hear and replaced the receiver.

"He'll be out in a moment."

I waited beside a noticeboard covered with wildfire prevention posters and a hand-drawn map of route closures. One marked area caught my attention. Somebody had circled Black Crag Mine in pencil and written NO PUBLIC ACCESS - UNSTABLE WORKINGS.

"Martin Shaw?"

I turned.

The man approaching was in his early forties, tall, with sandy-brown hair beneath a Forestry and Land Scotland cap. He wore cargo trousers and a waterproof jacket. A folder was tucked beneath one arm and he carried a flask in his other hand.

"That's me."

"Alastair Boyd. I'm the hydrologist here." He shook my hand with a firm grip and an even manner. "I hear you're looking into metallic-tasting water."

"That's right. I've completed the initial run, but I may need to return if anything appears in the results. I don't want to trouble your office every time I reach a gate."

"Makes sense." He gestured towards a side room. "Let me find you a map."

I followed him into a small office with filing cabinets and a laminated topographic map fixed to the wall. He took a folded district map from his folder and spread it across the desk.

Forestry Road 12 ran along the northern side of Loch Garve Reservoir, with smaller spurs branching in several directions. Alastair had marked some in red ink.

"These are the principal locked gates." He pointed to three positions. "This one is at the junction near Muirside Lane. The code is 4729. This one is farther east, beyond the reservoir. Code 8163. And this one here..."

He tapped a spur that divided southwards and climbed towards higher ground.

"It leads towards Black Crag Mine. The code is 3255, but I wouldn't go up there unless you had a specific reason."

I wrote the combinations in my notebook.

"Why not?"

"The old workings are unstable. We get regular rockfall. There have also been reports of somebody camping near the site. Probably harmless, but you should know."

I studied the map. Black Crag Mine lay roughly four miles north-east of Allt Ruadh Road.

"What sort of reports?"

Alastair shrugged. "A couple of walkers saw a camp. They didn't approach it. It could be somebody homeless or simply a person passing through. Forestry staff don't get into that area much now. The route was closed last year."

"Understood."

He folded the map and handed it to me.

"That should cover you. Watch for deer if you're driving after dark. We've had several on the reservoir road."

"I appreciate it."

I took the map, shook his hand again and left.

Back in the Defender, I checked the combinations against the marked gates and traced the routes with my finger. Three gates and three codes. Enough access for future monitoring without having to ring the office from each barrier.

I folded Alastair's map into my jacket pocket and started the engine. The dashboard clock showed 17:42. I had perhaps an hour of usable light remaining.

Not enough for fieldwork, but enough to scout the accessible roads.

I drove east, turned onto Forestry Road 12 and continued beyond the turning for the last private borehole. The surface grew rougher, gravel becoming dirt with deep wheel ruts. My headlights caught the trees crowding both sides.

After two miles, I reached the first gate Alastair had marked. A steel barrier crossed the track, secured by a combination padlock. I got out and entered 4729.

The lock opened.

I drove through, stopped and secured the gate behind me. Standard practice. You did not leave forestry gates open.

Another mile on, the road divided. The left-hand spur led towards the reservoir. The right climbed into higher ground. I took the right, following the map.

Gravel became dirt, then something that barely qualified as a road. Branches scraped along the Defender. I slowed to fifteen miles per hour and watched the odometer.

At 3.4 miles, I saw firelight through the trees.

I stopped and switched off the engine. I took my torch but left it unlit, then stepped into the rain and listened.

There was nothing but water dripping from branches and the faint crackle of burning wood. The camp stood about forty-five metres from the road in a clearing between two large spruce trees.

I approached slowly, placing my feet carefully to avoid breaking twigs. As I drew nearer, I saw a small tent, a tarpaulin tied between trees and a fire ring holding a respectable blaze. A man sat on a log beside it, stirring the embers with a stick. He was wiry, perhaps in his fifties, with greying hair beneath a waxed cap. He wore a checked work shirt and cargo trousers.

He did not appear surprised when I entered the firelight.

"Can I help you?"

His voice was flat. Neither welcoming nor hostile.

I stopped a few metres away. "I didn't mean to creep up on you. I saw the fire."

He looked me over, taking in the SEPA jacket, boots and torch.

"You're not Forestry and Land Scotland."

"No. SEPA. Martin Shaw. I'm dealing with water complaints in the area."

He nodded once and stirred the fire again.

"Graham Sayer. Volunteer route warden."

I looked around the camp. There was a rucksack, a cooler, a toolbox and a bundle of wooden stakes wrapped with red-and-white reflective forestry tape. His explanation appeared plausible before he offered any more of it.

"Are you out here alone?"

"Most of the time. I watch for fly-tipping, vandalism, that sort of thing. There isn't money for enough staff now, so I do what I can." He indicated the log opposite him. "Sit if you like. The rain isn't stopping soon."

I sat. The heat felt good. My jacket had soaked through.

Graham took a flask from his rucksack, poured coffee into a metal cup and handed it to me without asking. I accepted it.

"Thanks."

"You're the second person I've seen this week. Nobody used to come up here after September."

"Who was the first?"

"Some young man looking for his sister. Showed me a missing-person notice. Isla something. Seventeen, missing since last month."

Callum, presumably.

"I told him I hadn't seen her," Graham added.

I drank the coffee. It was strong and had no sugar.

"Have you heard about the others?"

Graham looked at me. "Yes. Four altogether now, isn't it?"

"That's what I've been told."

He put down the stick and leant back.

"The first disappearance was in April. But the later ones started after part of the Allt Ruadh Trail was reopened. The work finished in June. They brought in a crew, cut back the undergrowth, repaired drainage channels and installed new posts. Then three more young people vanished over the following months."

I kept my expression neutral.

"You think the route work is connected?"

"I think the timing is strange."

He took a small notebook from his shirt pocket and opened it.

"14 June, the crew finishes work on Allt Ruadh Trail. 23 June, Megan Pritchard disappears. 9 August, I find that broken-ring symbol painted on a drainage channel near the trailhead. Fresh paint. 17 August, Rhys disappears. I don't know his surname. 12 September, the same symbol appears on a post by the Muirside Lane turning. 19 September, Isla Fraser disappears."

I wrote down each date.

"Did you report any of this?"

"I tried. Police Scotland said the markings were probably vandalism. Forestry and Land Scotland said they would look into it, but I never heard anything more. The council said the route wasn't under their responsibility now." He closed the notebook. "So I kept watching."

"Have you seen the symbol anywhere else?"

"Three more times. On 2 October, it was painted on a barrier beyond the reservoir. On 7 October, it appeared on a tree near the Black Crag Mine access road. On 10 October, it was on a gatepost near here."

It looked back at me, always fresh, always the same: a broken ring bisected by a downward-pointing chevron. I thought about the symbol Callum had shown me. Same description, same clean paint.

"Have you got photographs of any of them?"

Graham pulled out his mobile, swiped through the pictures and handed it over. I saw the symbol on a metal drainage culvert, on a wooden trailhead post and on a tree. Every one looked identical, hand-painted but deliberate, not random tagging.

"Can you send these to me?"

He took my number and forwarded the images. My mobile buzzed four times.

"What's your reading of it?" I asked.

Graham stared into the fire.

"I think someone's marking routes, infrastructure and access points. I think the disappearances aren't random, and I think whoever's doing it knows these roads better than most people who live here." He looked up. "And I think nobody's going to do anything about it unless someone makes them."

I felt the same pull in my gut as before. Wrong. All of it.

"Are you planning to stay out here tonight?"

"Aye. I'll pack up tomorrow, head back into the village, replenish my supplies and come out again. I do a circuit. A week on, a couple of days off."

I stood and handed him the empty mug. "I appreciate the coffee and the information."

"Are you going to do something with it?"

"I don't know yet."

He nodded. He did not press me. He merely prodded the fire again and watched me walk back towards the Defender.

I sat in the cab for a minute with the engine off, staring at my mobile. Four photographs of the same symbol. Graham's dates lined up too neatly. A Forestry and Land Scotland crew reopened the trail. The symbols started appearing. Young people started disappearing. All within a five-mile radius. All close to forestry roads or infrastructure.

I started the engine, turned round and drove slowly back towards the main road. My headlights cut through the rain and darkness. The cool boxes rattled in the back. I had twenty-seven sample bottles packed in ice, gate codes for three locked spurs, coordinates for a painted symbol and a volunteer trail steward who had been recording things nobody else wanted to see.

The timing was wrong. The placement was wrong. All of it felt wrong.

I kept driving.

I returned to the Premier Inn beside the A9 on the outskirts of Inverness at about 20:30 that evening, 15 October. Room 214 looked exactly as I had left it, with equipment spread across one bed and my holdall on the other.

I put the cool boxes by the door and took out my laptop. I expected nothing but routine work: upload the GPS track, attach the chain-of-custody forms and send everything to Fiona with a note confirming that the samples were ready for collection by the approved laboratory courier.

It was standard end-of-day paperwork, the sort I had probably completed a thousand times.

I opened the mapping software and connected my GPS unit. The track loaded slowly, a thin blue line tracing the A82 and the connecting Highland A-road, then Loch Garve Road, Forestry Road 12 and the spurs. Each stop appeared as a dot where I had logged its coordinates: the first complainant's borehole, the second, the third, the five authorised follow-up monitoring points and the Allt Ruadh surface-water site. Nine sites. Twenty-seven bottles, three from each. They were all there.

But the line had gaps.

Three of them. Small breaks where the track simply stopped, then resumed farther along the road. I enlarged the first. It had occurred at about 14:45 near the locked gate on the spur beyond Loch Garve Reservoir.

I remembered that gate. The code was 8163. I had stopped to unlock it, driven through and secured it behind me, but the timestamps did not match. Gate unlocked at 14:43. Next recorded point at 15:07. Twenty-four minutes.

I stared at the screen. Unlocking a gate took perhaps two minutes, three if the chain was stiff. I would have driven through, locked it again and carried on. Five minutes at most.

I checked the second gap. The same thing: sixteen minutes missing on a straight stretch of road I knew I had driven without stopping.

The third gap lasted nineteen minutes. Together, the three gaps accounted for fifty-nine minutes that I could not explain, although the largest single gap was the first one, at twenty-four minutes.

I closed the laptop, opened it again and checked the battery and error log on the GPS unit. Full charge. No errors. I took out my backup GPS, an older Garmin I kept in the glove compartment, and connected that as well.

It showed the same gaps at the same times. Both units had failed to record the same intervals.

I sat on the edge of the bed and tried to remember. I had stopped at the gate. That much was clear. I had got out, entered the code and driven through. Then I had... what? Carried on, reached the next monitoring point and collected the samples. But I could not remember the drive itself.

There was the gate, then the sampling point. Nothing between.

I picked up my mobile and opened the call history. One outgoing call at 14:51 to Fiona's office number. Duration: one minute and forty-two seconds.

I had called to confirm something about the sampling protocol. I remembered that she had not answered, so I had left a voicemail asking whether she wanted duplicate samples from any boreholes showing high field readings. The call had taken place in the middle of the first gap. I had been conscious.

I had made a call, but both GPS units showed no continuous movement during that period, and I had no memory of stopping.

I stood and went to the cool boxes by the door. Twenty-seven sample bottles lay packed in ice, all correctly labelled and logged. I took one out and checked it. Its time matched my notes. Everything looked right.

I checked the second cool box. Again, everything was correct.

Then I saw the mark scratched into the blue plastic beside the latch.

A broken ring bisected by a downward-pointing chevron.

It was not painted. It had been cut deeply enough for me to feel the grooves beneath my fingertip.

I had handled those cool boxes a dozen times that day. I had loaded them, unloaded them and repacked them with two fresh 5 kg bags of ice. I would have noticed it.

I took my field kit and emptied it on to the bed. Nitrile gloves, sample bottles, labels, pens, pH strips, conductivity meter. Everything was accounted for.

I picked up the glove box and drew out the top pair. Grey grit coated the right glove, a fine powder almost like dust. I rubbed a trace between my fingers. It felt mineral, not like mud or soil. Something harder.

There were twelve gloves left in the box. I had started with twenty and used eight by double-gloving at four points where the handling protocol required it. The arithmetic worked, but I could not remember touching anything that would have left that residue.

I took three photographs of the symbol scratched into the cool-box lid. Then I photographed the glove and its grey grit, adjusting the light so the texture showed clearly.

I sealed the glove in a separate sample bag and labelled it with the date and time. It was not part of the field sampling chain and I marked that distinction plainly. Then I took tamper-evident SEPA evidence tape from my field kit, the sort we used for chain-of-custody seals, and ran strips across both lids. If anyone opened either cool box, I would know.

I was treating my own equipment like a crime scene.

That was what it had become, though, wasn't it? Something had happened during those missing fifty-nine minutes. Something I could not remember. And somebody had marked my cool box with the same symbol Callum had shown me on his mobile.

The same symbol Graham had recorded at six locations. The same symbol appearing near the places where four young people had disappeared.

I sat on the bed again and opened Graham's photographs. The broken ring and chevron on the drainage culvert. The same mark on the trailhead post. The same mark on the tree near Black Crag Mine.

The same mark on my cool box.

A television stood in the corner, but I did not switch it on. I did not sleep much that night.

The Police Scotland station in Strathgarve was a small brick building at the southern end of the village, sharing a car park with the council roads depot. I arrived shortly after 09:00 the following morning, 16 October, and sat in the Defender for a minute, trying to decide how to explain myself without sounding unwell.

Missing time. A scratched symbol. Grey grit. Four missing young people.

It sounded unwell.

I took my mobile, the cool box with the scratched lid and the bagged glove inside. The front office had a counter, two chairs and a noticeboard covered with community announcements. A woman in her early twenties looked up from her computer.

"Can I help you?"

I showed her my Scottish Environment Protection Agency identification. "I need to speak to whoever is handling the missing-person enquiries around Loch Garve."

She lifted a telephone, spoke quietly, then gestured towards the chairs. "Police Constable Drummond will be with you shortly."

I sat down. I did not wait long.

Police Constable Helen Drummond came through a side door about three minutes later. She was perhaps a metre seventy tall, fit, with blonde hair pulled tightly back, and wore a Police Scotland uniform and equipment belt.

She looked at me the way police officers look at people who arrive at a station on a Friday morning carrying a cool box and an evidence bag.

"You're with SEPA," she said.

"Martin Shaw. I'm investigating complaints about private borehole water near Loch Garve Reservoir."

"And you're here about missing people?"

"Yes."

She remained standing, her arms folded. "That isn't really within your remit."

"I know, but I found something yesterday, and I think it may be connected."

"Connected to what?"

I put the cool box on the counter and turned it so she could see the scratched symbol. "Someone cut this into my equipment yesterday afternoon. It is the same symbol that has been appearing around Allt Ruadh Road, and the same one Callum Fraser reported after his sister disappeared."

Drummond looked at the lid, then at me. "You're saying someone vandalised your equipment?"

"I'm saying I have fifty-nine minutes I cannot account for, spread across three gaps in two independent GPS tracks. The first gap lasted twenty-four minutes. I found this symbol on the lid and grey mineral grit on one of my gloves, and I don't remember touching anything that could have left it. It happened while I was near the forestry roads where those four young people went missing."

Her expression did not change. "You're reporting missing time."

"Yes."

"And you believe it is connected to people reported missing?"

"They're not runaways. Callum told me his sister had seasonal work arranged for the Christmas holiday and was preparing her university applications. She did not simply leave."

Drummond's jaw tightened slightly. "Mr Fraser has a theory. We have investigated his sister's disappearance. We have investigated all four cases. There is no confirmed evidence of foul play."

"What about the symbol?"

"What about it?"

"It keeps appearing. The same design at the same sorts of location. I have photographs from six different sites, all within five miles of one another and all close to where the four disappeared."

"Young people mark things. It might be a trail sign or somebody's art project."

"This was carved into my cool box while I was working. That isn't tagging. That's-"

"Vandalism," she cut in. "If you want to report criminal damage, I can take a statement. But missing time isn't something we can investigate without evidence that an offence occurred."

I opened the GPS track on my mobile. "I've got timestamps showing the gaps. I've got the call history proving I was conscious during one of them. I've got the mark and residue I cannot explain. Something happened out there."

Drummond studied the screen for perhaps five seconds before handing the mobile back.

"You stopped somewhere and lost track of time. It happens. It doesn't mean a crime occurred."

"Four young people," I said. "All missing since spring, all from the same area."

"Different months and different circumstances." Her tone remained flat and controlled. "Two of them were over eighteen. They were legally adults and free to leave if they chose."

"Their mobiles all stopped reporting from the same area, didn't they?"

That produced a reaction, though only a small one. Her eyes narrowed.

"How do you know that?"

"Callum mentioned it when he described the report."

"That information isn't public."

"He is Isla's brother. You told him."

Drummond exhaled slowly. "Their mobiles last reported from the same general area, yes. A forestry road near the reservoir. That is not unusual. Coverage is poor out there. Batteries fail. People switch phones off. Phones get damaged. It does not establish foul play."

"It establishes a pattern."

"It establishes poor mobile coverage."

I placed the evidence bag containing the glove on the counter and explained the grit and the scratched mark. She glanced at the bag but did not touch it.

"I cannot explain what you did or did not touch during your working day, Mr Shaw. Symbols painted or scratched on public infrastructure are not evidence of criminal activity unless they are threatening or linked to a verified incident."

"They are linked to four disappearances."

"They are linked, at most, to cases being treated as voluntary disappearances or possible accidents," Drummond said. "There were no witnesses, no signs of struggle and no remains. Only people who stopped turning up, and this mark."

She hesitated for a fraction of a second.

"There is a small independent kirk group that uses a similar marking. A ring with a descending shape. They say it represents grace coming down, or something of that sort. They meet in a converted steading south of the village and occasionally paint it near trailheads."

"Harmless kirk groups don't carve symbols into agency equipment."

"You don't know who carved it. It could have been anyone. It might have been there before you noticed it."

"It wasn't."

"Are you certain?"

I did not answer, because I was no longer certain. I had handled the cool boxes repeatedly, but had I inspected every surface? Perhaps I had missed the mark earlier. Perhaps the grit had been on the glove since the previous morning and I had not noticed it. Perhaps I was finding a pattern because I had begun to expect one.

Drummond's expression softened by a degree.

"I understand that you're concerned. But what you're describing - missing time and strange markings - is not something we can investigate without evidence of an offence. If you want to report criminal damage, I'll take the details. If you want to report trespass or interference with SEPA property, I can record that too. The missing-person enquiries are separate, and they are being handled according to procedure."

"What procedure? Waiting until somebody finds a body?"

Her face hardened again. "We follow procedure, Mr Shaw. We investigate reports. We interview witnesses. We co-ordinate with other services when necessary. We do not pursue theories based on graffiti and GPS faults."

"It isn't graffiti, and it isn't a fault."

"Then what is it?"

I had no answer.

Drummond took a form from beneath the counter and drew a pen from her pocket. "If you want to report criminal damage, I'll take your statement. Otherwise, I recommend that you return to your environmental work and allow us to handle the police enquiry."

I looked at the cool box, the scratched symbol and the bagged glove.

"Yes," I said. "I'll make the report."

She began writing.

I sat in the Defender outside the station for perhaps ten minutes before taking out my mobile. Fiona needed to know. That was what I kept telling myself. She was my supervisor. It was her case. The procedure was simple: unusual findings went up the management chain.

I rang her office number. She answered on the second ring.

"Mercer."

"It's Martin. I'm still in Strathgarve. Something has come up."

"Have the samples gone?"

"They're sealed and ready for the approved courier. Listen, I need to tell you-"

"Martin, I don't have time for this. Dispatch the samples. Complete the case. That is the assignment."

I pressed the mobile closer to my ear. "There's a pattern here. Four missing young people since spring, all within five miles of the complaint addresses. I found a symbol scratched into my cool box. It is the same mark appearing around-"

"A symbol?"

"A broken ring bisected by a downward-pointing chevron. It is on my equipment and on trail markers near the places where they disappeared. My GPS tracks also have gaps. Fifty-nine minutes in total. I cannot remember stopping, but both units-"

"You're telling me you lost track of time during fieldwork."

"It's not that. The timestamps don't match."

Her voice flattened. "You've worked in the field for ten years. You know how this works. We sample. We test. We report. We do not chase conspiracy theories about graffiti and runaways."

"They're not runaways. I spoke to the brother of one of them. Isla Fraser, seventeen. She had work arranged for Christmas and was preparing university applications. Her mobile stopped reporting in the same area as the others."

The silence lasted long enough for me to wonder whether the call had dropped.

Then Fiona said, "Where did you hear that name?"

"Callum Fraser. He works on the till at the local Co-op Food. He made reports to the police and called our hotline three weeks ago. Didn't you see it?"

"I see a great many calls, Martin."

"This one is connected. The water complaints, the Forestry and Land Scotland roads, the missing people. It is all within the same radius. Somebody is using those access points. The timing lines up with-"

"Stop." Fiona's tone turned cold. "Listen carefully. You were assigned to investigate complaints about private water supplies. That is all. Not missing people, not symbols and not theories about young adults who may have taken a lift to Glasgow. Do your job."

My jaw tightened. "I am doing my job. But if something else is happening here-"

"It isn't. And even if it were, it would not be within SEPA's remit. Dispatch the samples. Submit your report. Close Strathgarve by the end of the week. Someone in the Scottish Government has been asking about response times for rural complaints, and I need this case finished. Understood?"

I did not reply at once.

"Martin?"

"Understood."

"Good. I'll authorise overtime for tomorrow if you need additional time to finish the work. Just get it done."

She ended the call.

I sat staring at the mobile. The Scottish Government. That was new. Fiona had never mentioned political pressure over a routine private-water complaint before. And the way she had reacted when I said Isla's name had not sounded dismissive. It had been something sharper.

I started the engine and pulled out of the car park.

The email arrived twenty minutes later while I was stopped in the village. My mobile buzzed twice. I glanced down.

From: Fiona Mercer.

Subject: Re: Strathgarve overtime approval.

Time: 10:47.

I pulled into a parking space outside the ironmonger's before opening it.

Martin,

Overtime approved through Friday. Complete the northern monitoring grid and use the Black Crag route to reach the upper groundwater monitoring boreholes. It is quicker than looping back through Forestry Road 12. Gate code 3255. Close this out and return to Inverness.

Fiona

I read it twice, then a third time.

I had not mentioned Black Crag to her. I had not referred to the mine, its access route, the northern grid or any upper monitoring boreholes during the call or in an email. Alastair Boyd had marked the mine on the Forestry and Land Scotland map he gave me the previous day, but that document was still folded in my field case. I had not photographed or sent it to anyone.

I did not even know what the northern monitoring grid was. The assignment file contained three complainant boreholes and five pre-authorised follow-up monitoring points, nothing described as a northern grid. There was no upper set in my folder.

I checked the sender's address. It was Fiona's genuine SEPA address, the one she always used, but the tone was wrong. Fiona wrote in clipped managerial fragments: Approved. Complete by Friday. Report when finished.

This message contained more detail than she had ever given me. A precise route. A gate code. A specific instruction to use Black Crag.

I opened Alastair's map and followed the red line marking the spur towards Black Crag Mine. It left Forestry Road 12 about three miles beyond the reservoir gate, climbed north-east into rougher ground and ended at the old workings. Alastair had warned me about unstable tunnels, rockfall and somebody camping nearby. Graham had recorded the symbol near the mine on 7 October.

I sat with the engine idling and the email open on my screen. It felt like a shove.

I saved the email, took screenshots and forwarded copies to my personal account. Then I put the Defender into gear and headed east.

The gate to Black Crag Mine was open.

I reached it shortly after noon and sat staring through the windscreen. The mesh barrier stood wide, pushed back against the bracken. There was no chain across it and no padlock on the post.

I switched off the engine and got out. Alastair had marked the gate as locked. Code 3255. I had written it down with the other access codes. Yet the gate stood open as though somebody had driven through and had not bothered closing it.

The padlock lay in the ditch about two metres from the post, still attached to a short length of chain. I crouched without touching it.

The shackle had not been cut. It had melted. The metal was bubbled and warped, the keyway deformed into a black smear. The chain was scorched.

I took three photographs, then looked along the road beyond the gate.

There were fresh tyre tracks. Two sets. One was older, perhaps a day or two old and already softened by rain. The other retained sharp edges and had probably been made that morning.

I returned to the Defender and drove through.

The first groundwater monitoring borehole stood about half a mile up the spur, precisely where Alastair's map indicated. A small clearing opened on the left-hand side of the road. A metal casing rose about a metre from the ground, topped with a rusted cap, and a SEPA identification tag was bolted to its side.

I had seen hundreds like it. It was a standard installation from decades earlier, intended to monitor groundwater around former mines or industrial ground. Many were effectively abandoned but remained on the official register. Somebody was meant to inspect them annually. Often, nobody did.

I parked and approached with my clipboard and GPS unit. The tag read:

MW47LG - Loch Garve Groundwater Monitoring Borehole 47.

I logged the position, then crouched to inspect the cap.

That was when I saw the symbol painted beneath the metal tag.

A small, neat broken ring bisected by a downward-pointing chevron.

I froze.

The paint was fresh, the same cheap latex as the other marks. This one had been concealed. Nobody would see it without crouching low and looking beneath the tag.

I took six photographs from different angles, ensuring that the texture of the paint and the SEPA serial number appeared in the same frame. Then I opened the GPS application and recorded the position again:

57.173642, -4.702918.

I saved it, checked it and stored a duplicate on my field tablet.

The road continued north-east for another quarter of a mile before ending at the mine. Trees crowded both sides. There were no other vehicles and no noise except rain ticking against leaves and the distant rush of runoff below the road.

I returned to the Defender and drove on.

Black Crag Mine appeared to be sealed. I parked in the small turning circle at the end of the road and stared at the entrance. It was roughly two and a half metres high, framed with old shoring timbers that had turned grey and soft with rot. Planks were nailed across the opening in an X, with a weathered yellow sign wired at their centre.

DANGER

UNSTABLE MINE

NO ENTRY

FORESTRY AND LAND SCOTLAND

Something was wrong.

I got out and went closer. The boards were old. The nails were old. But the earth before the entrance had been disturbed and scraped, as if something heavy had recently been dragged across it.

There was smoke as well. Not much, only a thin thread escaping from behind the timber frame on the left.

Cold smoke. The sort from a fire that had been banked or almost put out.

I crouched beside the gap between the boards and the rock face. It was perhaps sixty centimetres wide. Just enough.

I took the head torch from my jacket pocket and switched it on. Its beam cut through the darkness. The tunnel sloped down between roughly hewn walls, with support beams at intervals of about three metres.

There were footprints in the dirt.

Several sets. Recent.

I should have telephoned someone. Helen Drummond, Police Scotland, the Forestry and Land Scotland district office. Anyone.

I did not.

I squeezed through the gap.

The tunnel smelt of cold stone, smoke and something else. Something organic. Not decay, only presence, as if people had been living there.

I kept the beam low and moved carefully. The floor descended at perhaps ten degrees and was uneven, slick where water seeped through cracks in the rock. The timbers overhead creaked.

I did not look up.

About nine metres in, I found the first candle. It stood in a glass jar on a flat stone beside the wall. Wax pooled at the bottom and the wick had burnt away.

I continued.

Fifteen metres. Another candle, this one with two or three centimetres of wax remaining.

Twenty metres. Food wrappers. An oat bar. An empty dried-meat packet. A plastic water bottle.

I stopped and listened.

Nothing.

The tunnel widened roughly thirty metres from the entrance into a chamber perhaps six metres across. The roof rose to nearly four metres and was held by a grid of timber supports that looked newer than those nearer the entrance.

Somebody had reinforced the chamber. Somebody had been living there.

Three rucksacks stood in a line against the left wall.

I went over and crouched beside them. The first was a black Berghaus. I opened the main compartment and found a purse containing a provisional driving licence.

Megan Pritchard. Sixteen. Brown hair. Address in Inverness.

The second rucksack was a green Vango. A wallet inside held identification for Jamie Kerr, nineteen, with an address in Strathgarve.

The third was grey and contained no wallet. A strip of white sports tape had been fixed to one strap, the name written in ballpoint pen.

Isla Fraser.

I stared at it.

Then I heard voices.

They came faintly from deeper underground. Two people speaking, perhaps another ninety metres away. I could not distinguish the words, but I recognised the cadence: one voice low and even, the other higher and clipped.

Footsteps echoed towards me.

I switched off the head torch and pressed myself against the wall behind a support beam. The voices grew louder.

"I told you to wait until Friday."

"We're out of time. The samples are already flagged."

I knew that second cadence. It sounded like Fiona.

I kept the light off. The voices continued, which meant they had not heard me.

"Keep the figures clean," a man said. His voice was calm. He was not shouting. "The council needs three more samples by Tuesday, and we need the next arrival on schedule."

I pressed my back against the tunnel wall. Cold soaked through my jacket. My thumb rested on the switch of the head torch. Part of me wanted to turn it on simply to prove that I was not imagining any of this.

I kept it dark.

The higher voice came more clearly. "Boyd has already filed the access variance. Forestry and Land Scotland won't touch it."

Alastair Boyd. The hydrologist who had given me the gate codes the previous day.

A third voice answered. I thought it was Fiona. I could not be certain. The wet stone distorted it, bending the echoes in ways the tunnel's shape did not explain. But I was perhaps seventy per cent sure. The cadence was hers: clipped and managerial, the voice she used when closing down a problem.

"SEPA has handled it," the voice said. "Shaw will log the samples, submit the report and move on. He always does."

My teeth began to hurt. It was not a dull ache but pressure building behind my molars.

Then another voice spoke, and it was not Fiona.

It was lower and thicker. It travelled through the stone like oil through water. I felt every word in my jaw.

"At the quarter-day. Three more. Perhaps a fourth."

I stepped back.

My boot scraped against stone.

The voices stopped.

I did not wait. I turned towards the entrance and moved with one hand against the wall. No light, only my memory of the straight route I had followed inside.

Nine metres. Fifteen.

The gap should have been ahead.

It was not.

The wall curved left where it should have remained straight. I stopped and felt along the rock. It was wet and cold, and its shape was wrong. I had walked directly into the mine. There had been no turns and no branches, only one descending passage.

Now the tunnel forked.

I retreated three steps and tried again. The same thing. One passage led left and the other right. Neither matched my memory.

My hand found the switch on the head torch. I did not press it.

Footsteps sounded behind me, slow and unhurried.

I took the right-hand passage, moving faster. My hands scraped rock and my boots slid on the wet ground. The air smelt of smoke and stone and something organic that I did not want to identify.

Six metres. Nine.

Then I saw it.

Daylight. Weak and grey, but daylight. The gap between the boards and the rock face.

I started towards it.

Alastair Boyd stepped into the opening. His head torch was off. He stood backlit by the rain outside, hands in the pockets of his waxed jacket, as calm as if he had been waiting for me.

"Martin," he said. "You should have stayed in Inverness."

I did not answer.

He took one step inside. He did not block the gap completely, but he narrowed it.

"This isn't what you think," he said. "The mine is a necessary exchange. Strathgarve survives because of it. Three thousand two hundred people. Jobs, schools, infrastructure. Do you think Forestry and Land Scotland keeps roads open here for nothing?"

I watched his hands.

"We manage the flow," Alastair said. "Three each quarter, with an occasional fourth. Runaways, drifters, people no one follows properly. In return, the village receives investment. The council gets quiet boreholes. SEPA gets clean paperwork. Everyone benefits."

"Isla Fraser wasn't a runaway."

Alastair tilted his head. "Callum made complaints to three organisations. None of them acted. Do you know why? Because the ring and chevron erase records and blur recollection. You felt it yourself."

"Fifty-nine minutes gone."

"Yet you rang Fiona. Logged coordinates. Kept working. You did not even notice."

My jaw ached.

"The symbol marks the route," he continued. "It keeps people from remembering. Keeps mobiles from reporting. Keeps investigations from reaching a conclusion. You've seen it six times now. On your cool box, on your notes, probably on your Defender."

I had not checked the Defender.

Alastair stepped closer.

"You'll forget this conversation within an hour. You'll submit your samples, file your report and ask for a transfer. The case will be closed. No contamination source identified. You'll move on."

Something entered the weak light behind him.

It was not Alastair. It was not Fiona. It was roughly human in shape, but its proportions were wrong. Its arms were too long and its head too narrow. Its skin looked burnt, not freshly but long ago, as though someone had been caught in a mine explosion decades earlier and left to dry in the dark. Its eyes were filmed white, without pupils.

It smelt of wet ash and rotting cloth.

It passed Alastair without touching him. Alastair did not react.

The thing stopped about a metre in front of me.

I could not move.

It extended one hand. The fingers were too thin and the nails were black. It touched my forehead.

Everything snapped into focus.

I did not see the missing people in the chamber around me. What the creature gave me was a vision of another place, deeper or elsewhere, as immediate as sight.

Isla Fraser, seventeen, sat against a stone wall with cable ties around her wrists. Her eyes were half-closed. She looked drugged but alive. Jamie Kerr, nineteen, was beside her. Megan Pritchard, sixteen, lay slumped in a corner. Rhys, whose surname I did not yet know, lay on his side, breathing slowly. He looked about twenty-one.

All four were in a separate chamber lit by candles. The walls seemed at once to be rough mine stone and curved concrete slick with drainage water, as if two underground places had been folded together. Bracken roots showed through a crack overhead. Something stood above the captives holding a calendar marked for a quarter-day ritual three nights later.

The creature was showing them to me deliberately. I understood that much, although I could not understand why.

The vision held for five seconds.

Then the hand withdrew.

I staggered backwards and reached into my field kit. My fingers closed around the first solid object they found: a glass sample bottle filled with water from Allt Ruadh.

Alastair began to speak.

I swung the bottle into his knee.

He went down. I did not wait to see whether he rose again.

I threw myself past him, squeezed through the gap and landed in the mud outside. Rain struck my face, cold and real. I ran for the Defender.

Something cracked behind me.

Not wood. Stone.

I looked back. The supports were failing. One beam snapped, then another. The rock above the entrance sagged and dust poured through the gap. Alastair was still inside or immediately behind the opening. I could not see Fiona and had never seen her in the mine at all.

I reached the vehicle, pulled open the door and seized the red emergency beacon flare from the incident kit beneath the seat. I removed the cap and struck it.

Red fire burst into the rain.

I threw the flare towards the entrance. It landed about three metres from the gap, burning fiercely.

The mine made a sound like teeth grinding.

The entrance collapsed.

It happened at once. The boards burst outwards. The timber frame snapped and the rock face above the adit dropped straight down. Dust and smoke rolled across the turning circle and struck me nearly ten metres away.

Then there was only the rain.

I stood clutching my keys and breathing hard, staring at the pile of rock and shattered timber where the opening had been. There was no movement and no sound.

I got into the Defender and drove.

I did not stop until I reached the Garve Forest district office. Two vehicles stood in the car park. I pulled in beside a green Forestry and Land Scotland pickup, switched off the engine and sat for thirty seconds, trying to decide what to say.

Then I dialled 999.

The operator answered almost at once. I gave my name, my SEPA identification number and said I needed Police Scotland and rescue support for missing people connected to an active collapse at Black Crag Mine, off Forestry Road 12.

She asked whether anyone was injured.

"I don't know."

She asked for my location. I gave her the address of the district office and said I had photographs, GPS coordinates and evidence that four missing young people had been held underground before the entrance collapsed.

She told me to remain where I was.

I stayed.

Eighteen minutes later, three vehicles arrived: two marked Police Scotland cars and a Forestry and Land Scotland vehicle.

Detective Sergeant Moira Campbell got out first. She was in her late fifties, athletic, with dark brown hair and grey-green eyes. She came directly to my window and asked for my identification.

I handed it to her. She checked it, returned it and said, "You called about Black Crag Mine."

"Yes."

"You reported missing people."

"Four. Isla Fraser, Jamie Kerr, Megan Pritchard and Rhys, surname unknown. They've been missing at different times since spring."

"You saw them?"

"I was shown them. Alive. In a chamber connected somehow to the mine before the entrance collapsed."

Police Constable Euan Reid joined her. He was about a metre eighty-three, solidly built, with close-cropped light-brown hair. He wore a protective vest and had a calm expression that did not alter when I mentioned the collapse.

The third responder was Forestry and Land Scotland ranger Iain MacLeod, a lean man of about a metre eighty with black hair beneath a waxed cap. He remained a pace back, one hand near his radio.

Moira glanced at Euan, then looked at me again. "Show us."

I opened the photographs on my mobile. The symbol scratched into the cool-box lid. The melted padlock. The hidden mark on the groundwater monitoring tag. The broken ring and downward chevron painted on six different surfaces. Then I showed her the GPS tracks and their missing timestamps.

She studied the screen for forty seconds without speaking.

"You're saying someone was holding four people in an unstable mine," she said, "and you were inside when it collapsed?"

"Yes."

"Was anyone else inside?"

I hesitated. "Alastair Boyd. A Forestry and Land Scotland hydrologist. He was at the entrance when it came down."

Iain stepped forward. "Alastair Boyd works with our district teams."

"I know."

"Where is he now?"

"Inside, or immediately behind the entrance. He was still there when it collapsed."

Nobody spoke for five seconds.

Euan lifted his radio and called it in, requesting Police Scotland-coordinated mountain rescue, fire and ambulance support, and specialist crime officers.

We returned in convoy: my Defender, the two Police Scotland vehicles and Iain's Forestry and Land Scotland pickup.

The gate at Black Crag remained open. The melted padlock was still in the ditch. Moira photographed it before we continued to the mine.

The entrance had vanished beneath a slope of shattered rock and splintered timber. Dust was still settling through the rain.

Euan walked the perimeter while Iain examined the turning circle for tyre tracks.

Detective Sergeant Moira Campbell stood before the collapse with her arms folded, studying the mound of fallen stone.

"How long were you inside?" she asked.

"Perhaps ten minutes."

"You heard voices?"

"Three. Alastair Boyd. I think another was Fiona Mercer, my supervisor. And there was something else."

"Something else?"

"I don't know what it was."

She wrote that down. Forestry and Land Scotland ranger Iain MacLeod returned from the turning area.

"Two sets of tyre tracks," he said. "One matches the SEPA Defender. The other came from a medium-sized SUV. Both recent."

Moira looked at me. "You said you saw the four missing people."

"Yes."

"Where exactly?"

"Deeper in, in a separate side chamber. They were cable-tied, drugged and alive."

"Did you try to reach them?"

"No. Alastair blocked the way out. I had to get out."

Police Constable Euan Reid came back from the treeline. "No other vehicles and no camps. If anyone else was here, they left before the collapse."

Moira took out her mobile and made a call. She spoke for two minutes, mostly listening, then hung up.

"Police Scotland-coordinated mountain rescue is on its way," she said. "Police Sergeant Kirsty Munro is taking the lead. She'll widen the search corridor into the Allt Ruadh drainage. If those four are alive, we'll find them."

"They were in the mine," I said. "The entrance has collapsed."

"If there's another way into the workings, we'll locate it."

Iain walked over. "I tried Alastair Boyd. No answer. I rang the Garve Forest district office. They said he left at noon and hasn't checked in since."

Moira looked at the rock pile, then back at me.

"Did you see Fiona Mercer inside?"

"No. I heard her voice."

"You're certain it was hers?"

I wasn't. The stone had warped the sound and cadence, but I told her I was about seventy per cent certain.

She wrote that down as well.

They kept me at the site for three hours. Moira took my statement while Euan photographed the entrance, the turning area and the tyre tracks. Iain coordinated with the Garve Forest district office and the emergency services.

At 16:47, Police Sergeant Kirsty Munro arrived with the mountain rescue teams. She was about five feet five, with a sturdy build, dark brown hair and a firm mouth. She established a staging area in the turning circle and deployed teams throughout the drainage.

I handed over everything: my phone with the photographs, the duplicate GPS files from my tablet, my chain-of-custody notes, the separate evidence bag containing the glove and grey grit, and the sample cooler with the broken ring and downward-pointing chevron scratched into it. Kirsty logged every item.

At 18:15, one of the search teams radioed in. They had found three rucksacks near Allt Ruadh Trail, concealed in bracken close to an old forestry drainage line. Isla Fraser's name was written inside one of them. They were the same Berghaus and Vango rucksacks I had seen in the accessible section of the mine, but which had vanished after the collapse.

At 18:42, the teams found the missing people. They were not in the mine itself, but in a disused forestry drainage chamber half a mile to the east, hidden beneath dense bracken. All four were alive: Isla Fraser, seventeen; Jamie Kerr, nineteen; Megan Pritchard, sixteen; and Rhys Morgan, twenty-one. They were dehydrated, hypothermic and drugged, but alive.

The chamber should not have connected to the mine. Yet its stone-lined rear wall ran towards Black Crag, and the position of the captives matched the vision the underground thing had forced into my mind. Whether it had shown me where they had been, where they would be, or some impossible joining of the two places, I could not tell. Without that vision, we would not have known they were still alive.

Isla was conscious enough to say one word.

"Mine."

That was all.

They did not find Alastair Boyd. He had been inside, or immediately beside, the entrance when it collapsed. There was no sign that he had escaped.

They did not find Fiona Mercer either.

The three rucksacks I had seen underground were no longer in the accessible passage. The candles had vanished too. After responders cleared a narrow probe channel through the fallen stone, they inserted cameras into the entrance. The visible section of tunnel was empty, but the main workings remained inaccessible.

Moira asked me to return to the Police Scotland station in Strathgarve to complete my incident statements. I went with her. Euan sat in, and Iain attended as the Forestry and Land Scotland representative.

I took them through every detail: the gate code Fiona had somehow known without my telling her about Black Crag or the northern monitoring grid, the groundwater monitoring borehole, the voices, the recurring symbol and the thing that had touched my forehead. I explained the three gaps in my GPS record, totalling fifty-nine minutes, and that the first and largest gap lasted twenty-four minutes. Moira wrote it all down.

When I finished, she said, "We'll need you to remain available for follow-up enquiries."

I told her that was fine. She handed me a card with her direct number.

I drove back to the Premier Inn beside the A9 on the outskirts of Inverness. From there, I sealed the field samples in their cold-storage containers and submitted them to the laboratory through SEPA's approved courier, preserving the chain of custody. The bagged glove and grey residue remained separately logged as police evidence. Then I emailed Fiona, requesting an immediate transfer to any available post outside the Highland Council area.

She did not reply.

The following morning, I telephoned SEPA Human Resources directly. They told me Fiona Mercer had not reported for work in two days and was not answering calls. I submitted a second transfer request.

The private-water complaint was closed four weeks later.

The laboratory results came back clean. No source of contamination was identified. The official explanation was likely seasonal mineral leaching, with retesting in spring recommended if complaints continued.

I signed off the report from a desk in Fort William. My transfer had gone through.

Isla Fraser, Jamie Kerr, Megan Pritchard and Rhys Morgan recovered. They spent a week in hospital before being released to their families. Police Scotland opened a formal investigation, which was later passed to its specialist crime division.

Nobody was charged.

Alastair Boyd never turned up. Fiona Mercer has never turned up.

Black Crag Mine remained collapsed. I kept the card Moira had given me in my wallet. I stored the GPS track in three separate places. I kept the photographs, and I continued checking my records because those fifty-nine missing minutes are still there, logged, time-stamped and unexplained. The first gap still lasts twenty-four minutes, no matter how many times I examine it.

I told myself that I had got out. I had escaped. I had reported what happened, people had listened, and the four missing young people had come home alive.

But sometimes I look through my field notes and find broken rings bisected by downward-pointing chevrons that I do not remember drawing.

Sometimes I check my GPS and find coordinates I never entered. Sometimes I taste metal, like sucking an old copper coin, and cannot work out why.

I do not go near Strathgarve now. I do not accept assignments close to abandoned mines.

And I never ignore gaps in my timeline, because I understand how the pattern works. Any future lapse, any missing hour or unexplained detour could draw me back onto the same route I barely escaped.

So I check everything twice. I log everything.

And I keep moving.

That is all I can do.