The Voice Below Cairn Dhu

I climbed Cairn Dhu Fire Observation Tower at 03:45 on Tuesday, 6 August 2024, because Jamie Kerr had texted me the previous afternoon saying, "Can't do Tuesday. Any chance you can cover?"

I had said yes.

I had been awake since 08:00 on Monday morning. I needed the money, and the alternative was another night in my Inverness flat with my mobile full of voicemails from Fiona that I had not yet returned. So I drove for an hour and twenty minutes, taking the A831 and then the Cairn Dhu forestry track through Glen Affric, and began the climb in darkness.

Eighty-one steps. I had done it often enough that my legs knew the count before my mind did.

The tower cab stood at an elevation of about 870 metres, high enough for the exposure and the climb to catch in your chest by the time you reached the top. I unlocked the hatch, pulled myself through and locked it again behind me. Standard procedure. The cab smelled of old coffee and the pine resin carried in on boot treads.

I set my flask on the desk, switched on the bottled-gas heater even though it was not cold yet, and logged my arrival in the duty book: 04:03.

I had not spoken to Jamie directly. There had only been the text. The number was saved in my mobile as his, so I had not thought to question it. The sky was still completely dark, without the first trace of colour.

I made the initial perimeter sweep with the binoculars, working clockwise from magnetic north as procedure required. Nothing. No smoke, no torches, no fires where fires should not have been. The Scots pine and commercial conifers below the tower formed a black mass without detail. I logged the sweep and sat at the desk to wait for first light.

That was when I saw it.

Movement at the tree line, perhaps 180 metres from the tower. Something pale and low to the ground, passing between the trunks. My hand went to the binoculars before I had consciously decided to reach for them.

I raised them and focused. It was still too dark to distinguish any detail, but I could follow the shape by the way it interrupted the blackness. It moved without urgency. It did not have the quick, startled motion of a deer at dawn, or the loping gait of a fox following a scent trail.

It covered the ground at a deliberate, patient pace that did not match the behaviour of any animal driven by hunger or fear.

I kept the binoculars trained on it. It moved parallel to the tree line for perhaps thirty seconds, then turned deeper into the pines and vanished.

I lowered the binoculars. My hands were steady. In the daily observation log, I wrote: "04:15. Movement observed at tree line, north-west sector. Likely deer. No follow-up required."

Then I picked up the radio handset and pressed the transmit key.

"Affric Control, this is Cairn Dhu."

Static answered first. Then came a voice I knew.

"Cairn Dhu, go ahead."

Moira Campbell.

I had worked three seasonal rotations of overnight duties, and her voice was as familiar as the hiss of the bottled-gas heater. Medium-low, unhurried, with the restrained Highland cadence I had heard on countless radio checks.

"Moira, it's Callum. I've got a visual on something moving through the pines in the north-west sector, approximately 180 metres from the tower. Pale colouration, low to the ground. I couldn't identify it in the dark. I'm logging it as likely deer, but the movement pattern was odd."

There was silence, and not the comfortable kind.

Then she said, "Copy that, Callum. Do you want me to log it as anomalous behaviour?"

The response was right. The cadence was right. She had said my name exactly as she always did. But there had been a delay before she spoke. Not long, perhaps a quarter of a second, but enough for me to notice. It was as though my words had needed to travel somewhere farther away than Forestry and Land Scotland's regional control room near Fort William, about 95 kilometres distant, before they could be answered.

"No," I said. "Just a standard observation. Probably nothing."

Another fractional pause.

"Copy. Anything else?"

"That's all. Cairn Dhu clear."

"Stay safe up there, Callum."

The channel went quiet. I returned the handset to its cradle and sat looking at it.

The delay could have come from the radio repeater above Bealach an Fhraoich. It could have been atmospheric interference. It could have been any of a dozen things unrelated to that quarter-second gap between my words and her reply.

I turned back to the window. The tree line was a flat black silhouette against a sky beginning to grey at the edges.

The shape had gone.

I raised the binoculars and searched the sector again, slowly and methodically, overlapping each field of view as I had been taught. Nothing.

I should have left it there.

Instead, I reached for the tablet on the desk and opened the camera feed. Two summers earlier, more from boredom than necessity, I had fitted a Browning motion-activated infrared trail camera at the foot of the tower stairs. Whenever something crossed its field of view, it transmitted a time-stamped image to the tablet. Most of the pictures were of deer. There had been the occasional badger and, once, a rare pine marten whose photograph I sent to NatureScot.

I opened the most recent image.

The timestamp was 04:12.

The photograph showed the clearing below the stairs in flat infrared grey. The staircase itself was a geometric line rising out of the frame.

At its foot, in the centre of the clearing, stood something tall and pale in the heat image.

It was not a deer. It was not any animal I recognised. The silhouette had too many angles. Joints bent where joints did not belong. The limbs were too long, the proportions wrong in a way that made my eyes want to slide away from the picture rather than focus upon it.

At the top of the shape, where a head should have been, something suggested a face turned upwards towards the camera.

Not a face. Something arranged to approximate the shape of one.

I stared at the screen. My hands had gone cold. Behind me, the heater clicked and hissed, and I heard my own breathing more loudly than I wanted to.

The thing had been standing directly below me three minutes earlier, looking up.

I took out my mobile, found my supervisor's contact and called Martin Hargreaves.

The call connected on the first ring.

"Callum."

Not a question. A statement. My name spoken the way he had spoken it a hundred times before, in his level English baritone, without any dramatic inflection.

"Martin, I've got something at the tower. I need-"

"I know. Stay calm. Help is on the way."

I stopped. My hand remained on the tablet, the infrared image visible at the edge of my vision.

"I haven't told you what it is yet."

"You reported an anomaly. Control forwarded it. I'm arranging a response now."

The words were right. The tone was right. The certainty was wrong.

I had called Martin twice in three years, once to arrange a Scottish Ambulance Service helicopter evacuation and once over a confirmed wildfire. Both times he had asked questions first. What could I see? Where exactly was it? How long ago had it happened? The procedural intake always came before the response.

This time, he had begun with the response.

"What sort of response?" I asked.

"Officers from Cannich forestry station. They're twenty minutes away. I need you to remain in the tower and keep the door locked. Do not go outside. Do you understand?"

"I understand."

"Good. Now describe what you're seeing."

I looked at the mobile. The call timer was running. Fourteen seconds.

Martin's voice was patient and methodical, waiting for an answer. It was the same voice I had heard at briefings, over the radio and once at a retirement gathering in Inverness, where he had stood at a lectern and read a prepared statement about twenty-six years of service.

The cadence was exact. The register matched. But the quality of the question was different. This was not a supervisor taking an incident report. It was something filling in a form and accumulating detail.

"Callum, what are you seeing right now?"

I put the mobile face down on the desk without ending the call. Martin's voice continued through the wood, asking me to confirm my location, whether I could still see the shape and whether I had secured the door.

I took my personal mobile from my jacket and called 999.

A woman answered on the second ring, her voice professional and controlled.

"Police Scotland. What's your emergency?"

"I'm at Cairn Dhu Fire Observation Tower in Forestry and Land Scotland woodland near Glen Affric. I need police assistance, now."

A pause. A quarter of a second, perhaps less. The same fractional delay I had heard from Moira on the radio.

"Can you describe the nature of the emergency?"

"There's something outside the tower. I don't know what it is. It isn't an animal."

Another pause of the same length, as though my words were being received and processed before a reply was constructed.

"Are you in immediate danger?"

"I don't know. I'm locked inside. I haven't gone out."

"All right. Stay where you are. Police Scotland assistance has been requested, and the two Forestry and Land Scotland officers closest to you will attend first. Can you give me your exact location?"

I recited the Ordnance Survey grid reference from memory. The control-room operator repeated it back exactly.

Then she asked, "Is anyone else with you at the tower?"

"No. I'm alone."

"And you said you're locked inside?"

"Yes."

"All right. The nearest officer is Alastair Reid from Cannich forestry station. He's about twenty minutes away. Can you remain on the line until he arrives?"

I had not said that the door was locked, not precisely. I had said I was locked inside.

The tower cab had two entry points: the exterior door at the top of the stairs and the hatch in the floor opening on to the enclosed stairwell. I had locked both, but I had not told her that.

"What's Reid's first name?" I asked.

This time there was no pause.

"Alastair. He's on the overnight rota at Cannich."

That was correct. I had met Alastair once or twice. But the answer had come at once, without hesitation or any apparent need to check a rota.

"I need you to do something for me," the operator said. "I need you to unlock the door so Officer Reid can reach you more quickly when he arrives."

I ended the call.

My hand was shaking.

I placed the second mobile beside the first, which still lay face down on the desk with Martin's voice audible through the wood. It had become a low murmur, asking whether I was still there.

I leaned back in the chair and forced myself to think.

Every channel I had opened that night had led outwards. Radio to Moira. Mobile to Martin. The 999 call to Police Scotland. I had fed information into every one of them. The camera image had already revealed the tower's layout, the position of the staircase and the clearing below, but the calls had supplied more voices to reproduce, names to use and confirmation that I was alone.

With the 999 call, I had confirmed that a locked barrier was the only thing between me and whatever waited outside.

It had asked me to unlock it.

I looked at the tablet. The infrared photograph remained on the screen: the pale shape at the foot of the steps, its head turned upwards.

Timestamp: 04:12. I had logged the sighting at 04:15. The call to Martin had followed immediately, with the 999 call perhaps two minutes later.

But the text from Jamie Kerr, the one asking me to cover his duty, had arrived at 13:43 on Monday, 5 August 2024.

I had been in my Inverness flat, half watching a match I did not care about, when the message appeared from Jamie's number. Short and casual.

"Can't do Tuesday. Any chance you can cover?"

I had replied, "Yeah," and had not thought about it again.

I opened the message thread. The text was still there, sent from the contact saved as Jamie Kerr. It was the same number I had messaged a dozen times before, but I had not heard his voice. We had never telephoned one another. Everything between us had been by text.

I stared at the screen.

The camera had activated at 04:12. But the night might have begun at 13:43 the previous afternoon, before I had ever climbed the tower or seen the shape among the trees.

Before any of that, something had known how to reach me. It had known I would answer, known I would agree, known I would be here alone with no one expecting me and no change entered on the rota.

Martin's voice remained faintly audible through the desk. My own breathing seemed too loud in the quiet. The heater hissed behind me. Outside, the forest was silent.

I sat in the darkness and understood that everything I had said aloud that night had been used against me, and that I did not know when the night had truly begun.

I descended the interior stairs as quietly as I could, which was not very quietly. Every tread creaked. The timber was old and dry, and the tower did not care that I needed silence.

I kept one hand on the rail and moved slowly, testing each step before placing my full weight upon it. The reinforced hatch stood at the bottom of the stairwell, set flush into the platform floor. A steel bolt had been fitted underneath after storm-felled timber damaged the lower braces in 2022 and the structure had to be inspected and recertified. I had climbed past the repaired and strengthened sections on every duty since.

I crouched beside the hatch and drove the bolt home.

The noise was louder than I wanted: metal against metal, a clean mechanical snap carrying through the stillness.

I froze and listened.

Nothing came from outside. There was only the bottled-gas heater two levels above and my breathing, which I could not slow however deliberately I inhaled.

I picked up the fire axe from where it rested against the wall. It had a red fibreglass handle, ninety centimetres long, and a head sharpened the previous season. I had never swung it at anything except a training log.

I put my back against the wall beside the hatch and held the axe in both hands, the blade angled towards the opening. If the hatch gave way, I would have one clean swing before whatever waited outside was in there with me.

The testing began perhaps two minutes later.

It was not a knock at first, but pressure.

The hatch shifted in its frame by a few millimetres, no more. Something on the other side had placed its weight against it and was determining whether the barrier would yield.

The bolt held.

The pressure eased.

I did not move. My palms were slick against the axe handle. I tightened my grip and made my breathing as shallow as possible.

Then it knocked three times, each knock evenly spaced.

Knock.

Pause.

Knock.

Pause.

Knock.

The interval was wrong. Not fast and not slow. Mechanical. It was the spacing used by something that had learnt knocking was the correct behaviour when it wanted a door opened, but had never knocked on a door in its life and did not understand that the rhythm was meant to vary.

I stared at the hatch and did not answer.

My own voice came through the wood.

"Callum."

It was not a recording. It did not have the flattened sound of my voice played through a mobile or heard during a radio check. It was my voice as I heard it from inside my own skull, with the interior resonance that travelled through bone and tissue and never reached a microphone.

I heard the shape of my name exactly as I heard it when I spoke it myself.

My hands clenched around the axe. My vision narrowed to the seam surrounding the hatch, and I made no sound.

It could not have learnt that from the radio. It could not have taken it from a recording or a telephone call. Interior vocal resonance did not transmit. It was not something that could be captured unless something had been close enough, for long enough, to learn it.

That meant it had been near me before that night, and had remained near me long enough to study the way I sounded to myself.

That was new information.

It was worse than the image from the trail camera.

I did not open the hatch. I remained with my back against the wall, the axe in both hands, without moving or answering.

My legs began to cramp at about 05:30. I shifted my weight as quietly as I could and kept the blade angled towards the hatch.

As I waited, the earlier question returned. If it had reached me through Jamie's number before I climbed the tower, if the false request at 13:43 on Monday had brought me there, then none of this was coincidence. I had been brought deliberately to that place, alone, for a duty no one else knew I was covering.

I did not know whether Jamie had sent the message. I did not know whether Jamie was safe.

The knocking stopped during the grey hour before dawn.

I did not hear the thing leave.

The sky changed from black to colourless, the sort of early light that illuminated nothing and merely made the darkness less absolute. I stayed where I was.

My back ached. My hands were numb. I did not move until 06:15, when the sky had become pale enough for me to see the grain of the timber in the hatch.

I climbed back to the cab. My legs shook on the stairs.

The mobile still lay face down where I had left it. The false call with Martin's voice had disconnected while I was below. It was silent and remained so.

I picked up the radio handset and pressed the transmit key.

"Affric Control, Cairn Dhu."

The answer came with the ordinary lag of a tired person nearing the end of a long overnight duty. A pause of perhaps half a second, the sort produced by someone who had been staring at a quiet control board for hours and needed a moment to return their attention to the present.

"Cairn Dhu, go ahead."

I could not know whether the voice was genuine.

Certainty was no longer an instrument available to me. I could not trust a delay, and I could not trust the absence of one. I could not trust that the person answering was the person whose voice I heard.

"Requesting a physical check of the tower and access track. I had some activity overnight."

"Copy. I'll log it. Do you need anything else?"

"Negative. Cairn Dhu clear."

I returned the handset to its cradle.

The axe remained within reach, leaning against the desk where I could seize it in less than a second. Outside, the forest was still. There was no movement at the tree line and no pale shape in the clearing. The Browning camera had not activated again.

The question of Jamie Kerr sat beside everything else I could not answer. Unreachable and unverified, he was the person whose supposed absence had placed me in the tower. I did not know where he was or whether he was safe. I did not know whether the number saved in my mobile as his had been spoofed, compromised or had ever been safe at all.

I took out my personal mobile. The screen was still lit from the 999 call I had ended nearly two hours earlier. My thumb hovered over the contacts, then moved to the number I had been avoiding for six weeks.

The realisation that had driven me against the wall with the axe - that the thing outside had reproduced the interior resonance of my own speech, something no recording could capture - also told me what sort of verification I needed.

Not a test of delay. Not a procedural question or an operational detail. I needed something that existed only between two people who had never had a reason to perform it for anyone else.

Something that hurt.

I called Fiona Fraser.

She answered on the third ring, her voice rough with sleep and immediate worry beneath it.

"Callum?"

"Yeah."

"What's wrong?"

Not what time is it, or why are you calling. Only the question that mattered.

I sat in the chair beside the desk. The axe leaned against the filing cabinet within reach. Beyond the windows, the sky had changed from black to flat grey, colourless light making shapes visible without yet defining them.

"I need you to say something," I told her. "Something only you would know."

She did not ask why.

She was quiet for a moment. It was not the processed quarter-second delay of the voices that had answered me throughout the night, but the silence of someone who understood what I was asking and was deciding whether to give it.

Then she said, "Bracken. The old black lurcher with the failing hind legs. We called him that because once he settled somewhere, you could never shift him."

I closed my eyes.

I had not said her name aloud in six weeks. I had listened to her voicemails without calling back, because calling meant explaining why I had stopped coming home at regular hours, why I had accepted extra duties I did not need and why I had moved my belongings into the Inverness flat one car-load at a time without discussing it first. Calling meant admitting that I had chosen distance over the work of staying.

But she had given me Bracken's name without being prompted, and the reason for it. The old black lurcher we had put down in 2019 because his hind legs were failing and he could no longer walk. We had held him together on the table at the veterinary surgery, and I had cried harder than I had at my father's funeral.

We called him Bracken because, once he found a place in the sitting room, he rooted himself there for the day as stubbornly as growth on a hillside. We had never told anyone why. It belonged to us.

The verification worked not simply because the name was private, but because it came from someone who had no reason to keep me on the line. Fiona had no reason to ask me to unlock anything and no operational interest in what I did next. She was the opposite of every voice that had spoken to me since 04:12.

"I'm all right," I said.

"You don't sound all right."

"I will be. I just needed to hear you."

She did not hang up.

I could hear her breathing and the faint movement of bedding as she sat upright. She was in the house we had bought together in 2017, the one with good south-facing light in the kitchen and the decking I had never finished staining. I was in a cramped cab roughly 4.3 metres by 1.2 metres, high above Forestry and Land Scotland woodland in Glen Affric, holding a mobile to my ear with an axe within reach.

"You're going to explain this later," she said.

It was not a question.

"Yeah."

"All right."

She did not press. She simply stayed there.

I could picture her sitting at the edge of the bed in one of my old shirts, her hair loose, waiting. The sky outside completed its transition from grey to a pale blue-white, the sort of light that brought no warmth but made edges clear. The Scots pines and conifers at the tree line changed from black silhouettes to green.

Below the tower, the open ground between the foot of the stairs and the forest was sparse grass and peat-dark mud after an evening shower. It was the same view I had seen a hundred times over three seasonal rotations.

I kept the mobile to my ear and looked down at the clearing. Fiona's breathing was steady at the other end.

She did not ask where I was. She did not ask what had happened. She was simply present, the way she used to be in the kitchen while I made coffee before an early duty, sharing the space without speaking.

The light strengthened. Colour returned to the world: green at the tree line, brown across the clearing, grey on the wooden staircase.

Then I saw the impressions in the mud below.

They were not prints. They were long, narrow depressions, too many of them, arranged in a pattern unlike any gait I recognised. They circled the foot of the staircase in a slow spiral. Each was deep enough to suggest weight, but their spacing suggested movement without rhythm, without the regular alternating stride of anything that walked as living things walked.

I held the mobile against my ear. Fiona remained silent at the other end.

The clearing was fully visible now. The peat-dark mud was wet from the previous evening's shower, and the impressions were clear enough for me to count if I wanted to.

I did not want to.

I stayed on the line with Fiona while the sun rose, for ninety minutes or perhaps longer. Neither of us said much. Once, she asked whether I wanted her to come out. I told her no, and she did not push.

The colour continued to deepen in the clearing. Green trees. Brown ground. Grey timber. The impressions remained where they were, dark and wet in the August mud.

At 08:00, I heard an engine.

A white Forestry and Land Scotland 4x4 came along the access track from Cannich forestry station. Two officers climbed out. I recognised the senior one immediately.

Alastair Reid was in his mid-forties, with close-cropped hair turning grey, and had worked around Glen Affric long enough not to waste time on small talk. The younger man was Forestry officer Lewis Grant, about thirty and stockily built.

Alastair looked up and nodded towards me through the cab window.

"I have to go," I told Fiona.

She said my name once, quietly, and then let me end the call.

I descended the interior stairs with the bolt still secured and opened the reinforced hatch from underneath. Alastair was standing at the foot of the exterior staircase when I emerged. Lewis was already walking the perimeter of the clearing, his radio clipped to his shoulder.

Alastair looked at me, then past the tower entrance and down at the mud.

"You said something was outside," he said.

"It was."

"Is it still here?"

"No."

"Did you hear it leave?"

I shook my head.

Alastair crouched at the foot of the stairs. In full daylight, the impressions were clearer than they had been at dawn. Long and narrow. Too many of them, arranged in a slow spiral around the staircase without following any gait I recognised. Each mark was deep enough to imply weight, but the spacing was wrong. No regular alternation. No rhythm.

Alastair took a service-issued compact Canon camera from his belt and photographed the impressions from three angles. Then he stood, checked the screen and photographed them again.

He said nothing. He simply looked at them for a long time, the camera hanging from his wrist.

Lewis returned from the perimeter and stopped beside him. He looked at the impressions, then at Alastair, then back at the ground.

"What do you think?" Lewis asked.

Alastair did not answer. He was still staring at the mud.

I told them what had happened. All of it. The shape at the tree line at 04:12. The image from the trail camera. The voices on the radio and the mobiles. The knocking. The thing outside using the interior resonance of my own voice, the sound I heard from inside my skull when I spoke. I explained that I had bolted the hatch from within and held position with the fire axe until the knocking stopped before dawn.

When I reached the text from Jamie Kerr's number, Alastair interrupted me.

"Kerr didn't give up his duty," he said.

I looked at him.

"He reported to Cannich station early this morning expecting to work his normal shift. He'd also telephoned the station directly on Monday evening to confirm it. Then your genuine request for a physical check came through Affric Control at 06:15. Between the two, it was obvious something was wrong. That's why Lewis and I came straight here."

I opened my mouth to say I had received a message from Jamie's number, then stopped.

Instead, I took my mobile from my jacket. The screen was still smeared where I had gripped it too tightly during the night. I returned to Monday afternoon and turned the mobile so Alastair could read it.

The message remained there, brief and casual, in precisely the style Jamie used.

"Can't do Tuesday. Any chance you can cover?"

Alastair looked at the screen without touching the mobile. He took a small notebook from his jacket and recorded Jamie's number, the timestamp and the exact wording. His handwriting was small and methodical.

"Jamie was at Cannich this morning," he said. "He never surrendered the duty. Your 06:15 radio request is recorded by the real regional control room. That request, and Jamie turning up for work, are why we arrived at 08:00."

Something cold settled in my chest. It was not panic, but something slower and heavier.

"I wasn't covering for anyone," I said.

"No," Alastair replied.

Lewis shifted his weight. He looked at Alastair, then at me, then back at the impressions. He said nothing.

I stood holding the mobile with the message still on its screen.

I could have telephoned Jamie to confirm it. On Monday afternoon, sitting in the Inverness flat with three days' washing-up in the sink and six weeks of Fiona's unanswered voicemails on my mobile, I could have touched the number at the top of the screen and waited for Jamie to answer. It would have taken thirty seconds.

Instead, I had replied without thinking because the message sounded like Jamie, because I needed the money and because the alternative was another night alone in that flat. Nineteen hours awake, the long drive through darkness and the climb beginning at 03:45 - I had treated all of it as routine.

I had questioned none of it.

The thing in Glen Affric had not waited for me to arrive.

It had arranged my arrival.

"Did you find anything else?" I asked.

Alastair shook his head. "The access track is clear. No tracks leading towards or away from the tower. No vehicle marks. Nothing showing how it arrived or left."

"You didn't hear it leave," Lewis said. It was not a question. He repeated the fact as though trying to make sense of it.

"No."

"That means something."

Alastair looked at him. Lewis fell silent.

We stood in the clearing while the sun rose higher and the shadows shortened. The impressions remained wet and dark in the mud.

I thought of the thing circling the foot of the stairs before dawn. Patient and methodical. Learning the layout, learning my voice and learning to sound like people I trusted.

I thought of the message from Jamie's genuine saved number. How it had known how to reach me. How it had known I would come. How it had known I would be alone.

Lewis walked back towards the 4x4. Alastair remained where he was and examined the impressions once more. He did not crouch again. He simply stood with the Canon camera hanging from his wrist and his notebook in his hand.

Then he turned and followed Lewis towards the access track without speaking.

I remained in the clearing and understood that the night had not begun at 04:12. It began when I read a message from a number I trusted and did not think to verify. It began when I decided that nineteen sleepless hours and a long drive through darkness were routine enough not to question. It began when I climbed the first of eighty-one steps at 03:45, unlocked the tower and placed myself exactly where something had arranged for me to be.

That afternoon, I filed the report at the Forestry and Land Scotland district office in Inverness.

I completed the standard incident form, filling every box and leaving nothing vague. I sat at a shared terminal in the rear corner, beneath a fluorescent light whose faint buzz I had never noticed before trying to concentrate. The cheap keyboard clicked too loudly.

I entered the date, 6 August 2024, the location, my name and my job title.

When I reached the incident description, my hands became still above the keys because I had to decide how to express it.

I documented the anomalous behaviour across all three communication channels: the radio conversation with the voice of Moira Campbell, the mobile call answered in Martin Hargreaves's voice, and the 999 call supposedly handled by a Police Scotland control-room operator. I kept my wrists flat against the desk to stop my fingers shaking.

Then I entered the detail Alastair had confirmed at the tower. The duty-cover message had not come from Jamie Kerr. Jamie had telephoned Cannich forestry station directly on Monday evening to confirm his own duty and had arrived there early on Tuesday morning expecting to work. I had not been covering for anyone.

The cursor blinked at the end of the sentence. I could smell burnt, cold coffee in a mug left two terminals away.

I typed the next line.

"I had been summoned."

The sentence sat in 11-point Arial in the middle of a Forestry and Land Scotland incident form as though it belonged there.

I did not delete it. They could decide what to do with it.

I submitted the report digitally at 15:20 on 6 August 2024. An automated acknowledgement arrived forty seconds later. It was a standard receipt, and no human being could yet have reviewed what I had written.

At 16:03, a follow-up email appeared.

The sender line said Martin Hargreaves. The subject read: "Incident report: Cairn Dhu Observation Tower, 6 August 2024".

I opened it. The screen refreshed.

The first line said, "Your report has been received and reviewed."

My gaze returned to the timestamp in the header. 16:03. Forty-three minutes after submission.

I scrolled down.

The email stated that no further action was required at that time. It thanked me for remaining inside and following procedure. It said they were pleased I was safe.

My thumb rested against the edge of the trackpad. I realised that I had stopped breathing.

The final line appeared at the foot of the message in the same neutral typeface as everything above it.

"How are you feeling now that it's over?"

I read the email twice.

The phrasing was patient and careful. It had the same quality as the voices on the radio and the mobiles. It was not responding so much as collecting and confirming. The question was not casual concern. It was seeking information.

But there was something more specific this time.

The email did not mention Jamie.

Any real supervisor who had read the report would have flagged that detail immediately. The fact that I had been brought to the tower under false pretences was central to the entire incident. It was not something a supervisor would ignore in a follow-up. Martin would have asked questions. He would have escalated it.

Whatever had sent the email either had not read the report or had avoided the one fact it could not have obtained from anything I had disclosed over the compromised radio and telephone channels.

The information about Jamie had come independently from Alastair Reid, from Lewis Grant and from the records at Cannich forestry station.

It had come from somewhere the thing had not touched.

I didn't reply. Instead, I opened a new message and typed Dr Helen Mercer's email address from memory. My hands were steadier now. I forwarded Martin Hargreaves's email, then opened the file directory and found the infrared image from the Browning trail camera: the pale figure at the foot of the stairs, looking up.

I attached it. The progress bar filled, and I sat with my fingers resting on the home row, trying to decide how to phrase the question. In the end, I wrote only this:

The message claiming Jamie Kerr was ill, the one that brought me to the tower, did not come from the person it claimed to. It came from something that knew how to reach me before I was ever within range of Cairn Dhu. Does that match anything you have seen?

I read it once, moved the cursor to Send and clicked.

Dr Mercer had spent three years studying unexplained predator behaviour in the Highlands. She had taken my calls twice before without making me justify my certainty before she would listen. If anyone was going to examine this without dismissing it, it was her.

I closed the laptop. I didn't return to the tower.

I told Cannich forestry station that I couldn't work the rest of the week's rota. They didn't ask why. I drove down the Cairn Dhu forestry track towards the A831, with the windows open and the radio switched off.

The track was empty. The Scots pine and commercial conifers on either side were only trees again. No shapes moving between them. No pale figures testing the edges of the clearing.

There was only the August light, the dust and the sound of gravel beneath the tyres. I kept my speed steady and didn't stop until I reached the junction where the mobile signal returned. I pulled on to the verge, put the car in neutral, applied the handbrake and sat with the engine running.

I stayed there for perhaps five minutes before I called her again.

This time I wasn't asking for a name.

Fiona answered on the second ring.

"Fiona, I need to tell you what happened."

She said nothing. I could hear her moving, then what sounded like a door closing as she found somewhere private to listen.

So I told her.

I began with the text from Jamie Kerr's number on Monday, 5 August 2024, asking me to cover his Tuesday duty. I took her through the shape at the tree line at 04:12, the trail-camera image, and the voices on the radio, the telephone and the 999 line. I told her about the knocking. I told her about my own voice coming through the door, not as a recording or something played back, but with the interior resonance of my own speech, the way I heard it from inside my skull. I told her about the bolt, the 90-centimetre fire axe and the grey light that finally came.

I told her what Alastair Reid had confirmed: Jamie had reported to Cannich forestry station early on Tuesday, 6 August 2024, expecting to work his normal duty. He had never surrendered the shift. He had never been ill.

"That text didn't come from him," I said. "I didn't cover a sick call. I was summoned. It reached me before I was anywhere near that tower."

Fiona was quiet for a long time.

It wasn't the silence of someone deciding whether to believe me. It was the silence of someone hearing something that did not fit, and allowing it to settle before speaking.

"I believe you," she said.

I closed my eyes. It was the second time she had said it, and I had needed it both times.

"The thing is," I said, "I don't know what it is. I don't know how far it can reach. I don't know whether the email I received from Hargreaves's account at 16:03 was really from him or from something that had learnt to sound like him. I don't know whether it can reach you only when you're inside some sort of range, or whether it can initiate contact from anywhere. I sent everything to Dr Helen Mercer: the trail-camera image, the email and the detail about Jamie reporting for duty. But I don't know whether she'll reply, or whether her three years studying this sort of behaviour have already taught her that this is something you don't touch."

"So what do you know?"

I looked through the windscreen. There was dust on the glass and a crack running from the passenger-side corner that I kept meaning to have repaired.

"I know the difference between someone listening for me and someone listening to me. The voices on the radio and the telephone, and the email afterwards, were accumulating information. They were confirming things. Working towards access. You weren't. You answered when I called, and you didn't ask me to unlock anything."

She made a small sound. It wasn't quite a laugh, but it came close.

"That's the standard now? I didn't try to make you open a door?"

"Yes," I said. "That's the standard."

There was another silence.

"Are you safe now?" she asked.

"I think so. I'm at the junction. I'm heading back to Inverness."

"All right," she said.

She didn't tell me to be careful. She didn't tell me to call when I arrived. She said it simply, as an acknowledgement of where I had told her I was going.

"Fiona," I said.

"Yes?"

"Thank you for Bracken."

"You don't have to thank me for that."

I wanted to say something else. Something about the six weeks during which I had let her calls go to voicemail while I gradually moved myself into the Inverness flat. Something about how the name of our dead old black lurcher, whose hind legs had been failing, and the private reason we had chosen that name, had become the only verification I had left.

But I didn't. I only said I would call her later.

She said, "All right."

Then we ended the call.

I sat with the mobile in my hand. The question I had sent to Dr Mercer was still live.

The question wasn't what the thing had been, but how early it had begun. Whether it had been watching me for longer than that night at the tower. Whether it had learnt the interior sound of my voice somewhere else, at some earlier time I had failed to notice.

I had no answer. I had the text from Jamie Kerr's number. I had Alastair Reid's confirmation that Jamie had never sent it. I knew that I had been placed inside Cairn Dhu Fire Observation Tower, isolated at a particular hour on a particular night.

That was the boundary of what I knew. The boundary of what I didn't know was wider.

It had begun with the thing in the woodland around Glen Affric and ended with the number saved in my mobile as Jamie Kerr. I did not know where one edge met the other.

I put the mobile in the cup holder, checked the rear-view mirror and pulled on to the A831. The road towards Inverness was empty.

After the first few miles, the dense conifers gave way to open moorland and crofting country, with long sight lines beneath a flat August-blue sky. There were no clouds and no wind, only a faint shimmer above the tarmac ahead. I kept the windows open.

I held my speed steady. I didn't look at the mobile.

Somewhere beyond the 24-kilometre marker, I accepted that not knowing was the right amount, the only honest amount available to me. I had sent the question to Dr Mercer. She would answer or she wouldn't.

Either way, the question was live now. It was no longer contained within the tower, and it was not something the bolt or the axe could answer. How far back had the contact begun? Could the thing reach beyond the range of the trail camera and the radio? Was the number saved in my mobile as Jamie Kerr still sending messages?

I was about twenty minutes outside Inverness when the mobile buzzed in the cup holder.

I glanced at it. The screen had lit, with a notification banner across the top. I didn't reach for it immediately. I kept both hands on the wheel and watched the road.

The mobile buzzed again. A second notification appeared beneath the first.

I pulled on to the verge, applied the handbrake and picked it up.

There were two messages, both from the number saved as Jamie Kerr.

The first said, "You good?"

The second said, "Haven't heard from you in a while."

I stared at the screen. My thumb hovered over the notification. I could have opened it. I could have read the entire thread and searched the message history for something that showed when it had stopped being Jamie and become something else.

I didn't open it.

I held the mobile and felt its weight in my hand. I thought about the voices on the radio that had known exactly what I needed to hear. I thought about the thing that had learnt my cadence, my vocabulary and the interior sound of my own voice. I thought about the email from Hargreaves's account asking how I was feeling.

The mobile buzzed a third time.

Callum.

I looked at my name on the lock screen.

Before I severed anything, I preserved the evidence. I took screenshots of the notifications and the full message thread, exported the available message metadata and sent copies to Dr Mercer. I added the same files to the Forestry and Land Scotland incident record I had submitted at 15:20 that afternoon.

Only then did I open the contact settings, scroll to the number saved as Jamie Kerr and block it.

The screen went quiet.

I sat for a moment, looking at the empty road through the windscreen. Then I deleted the visible thread from my mobile.

Every message, every timestamp, the entire history back to March, when Jamie had first given me his number. It took three confirmations to erase it all. I tapped through each one.

When it was gone, I returned the mobile to the cup holder, checked the mirror and pulled back on to the road.

The question I had sent to Dr Mercer was still out there. She would answer or she wouldn't.

But the number that had summoned me to the tower, the first point of contact, the thing that had isolated me before it ever revealed itself, was gone from my sight now. Not answered. Not understood. Only severed.

I drove the rest of the way towards Inverness with the windows open and the mobile silent beside me.

Glen Affric remained behind me, where it belonged.