The Singing Stone

I arrived at the remote walkers' car park an hour early to check my kit one last time, although I had already checked it twice at the country-house hotel near Aviemore. It was force of habit after twenty years as a mountain guide. The morning air was sharp against my face, the sort of Highland chill that caught in your lungs if you breathed too deeply.

I leant against my ageing Land Rover Defender and watched the forestry road, waiting for the clients to appear in whatever luxury vehicles they had hired for the journey from Aviemore.

They arrived on time in a small convoy of two black Range Rovers, each of them probably worth more than I earned in a year. They rolled into the gravel car park, raising a haze of dust that shone in the morning light. I straightened and put on my professional smile as five men climbed out. They looked exactly like the photographs attached to the booking paperwork addressed to Callum Fraser, lead guide.

Oliver Grant emerged first, struggling with a rucksack that still had shop tags hanging from its straps. According to his forms, he was a technology executive, and everything about him suggested an office life, from his soft hands to the way he squinted at the sun as though it were an unexpected inconvenience.

"You must be Callum," he said, offering his hand. "The built-in sat-nav didn't cover half these roads. We had to follow actual signs like it was the nineties."

I shook his hand.

"Welcome to the Cairngorms, Mr Grant. The old ways still work best in places like this."

Rupert Hargreaves came next, a private-equity manager wearing walking boots so new that they squeaked. He moved with the careful precision of a man who had researched remote expeditions exhaustively online but had never been on one.

"The drive was rather scenic," he said in the polished tone of someone accustomed to boardrooms. "Though I'm surprised there hasn't been any mobile signal for the last thirty kilometres."

"That's part of the attraction," I said. "You're properly off-grid now."

Miles Redmond bounded out of the other Range Rover with a camera already in his hand. The commercial property developer had more gadgets attached to him than most professional photographers I knew: action cameras, a drone case and at least three mobile phones distributed among the pockets of his immaculate outdoor clothing.

"This light is perfect," he announced, photographing the mountains without offering so much as a hello. "Callum, you've chosen an incredible place. How many followers have you got? You ought to document these expeditions."

"I don't really use social media," I said, watching him adjust a camera that probably cost more than my monthly mortgage payment.

Dr Alistair Khan climbed out slowly, his attention fixed on the satellite phone in his hand. The chief executive of a British pharmaceutical firm frowned at the device as if it had personally offended him.

"Weak signal," he muttered. "Is that normal? My office needs to be able to reach me."

"It will come and go," I explained. "That's why we agreed the emergency procedure before the trip."

Graham Whitaker was the last to join us. He was already wiping sweat from his forehead despite the cool air. The North Sea energy executive looked uncomfortable in expensive waterproof clothing still stiff from the shop.

"This mountain air is thinner than I remember," he said, wheezing even though we had barely gained any height. "How far are we walking today?"

I gathered them around the bonnet of the Defender, where I had spread out a laminated Ordnance Survey Explorer map. Five faces regarded me with varying degrees of interest and apprehension.

"Welcome to a quieter part of the Cairngorms, gentlemen," I began, tapping the map. "We're away from the busiest paths and estates, and much of this ground is protected. We have roughly ten kilometres to cover before our planned first camp. The route begins on a forestry track, then becomes a narrower hill path after lunch. If all goes well, we'll have plenty of daylight for pitching the tents."

I gave them my standard safety briefing. I explained the agreed regrouping procedure if anyone became separated, handed out mountain-safety whistles and stressed the need to drink regularly. In a serious emergency, anyone able to make contact was to ring 999, ask for Police, then request mountain rescue. I carried a satellite messenger and personal locator beacon if the mobile network failed, as it almost certainly would.

"Before we leave, we'll do a final kit check," I said.

It was worse than I had expected.

Oliver had packed three pairs of shoes but no waterproof jacket. Rupert had brought a first-aid kit full of equipment better suited to a minor surgery, yet had forgotten a head torch. Miles's rucksack was overloaded with cameras and batteries but light on essentials. Alistair had packed enough medication to stock a small dispensary but no proper insulating layers for a cold night. Graham had somehow brought a summer sleeping bag despite the clear guidance we had sent about overnight temperatures.

I kept my expression neutral while I took spare supplies from the Defender and my own expedition kit: waterproof jackets, head torches, foil survival blankets and purification tablets.

"These will cover the gaps," I said diplomatically. "No extra charge."

"You came prepared," Rupert observed, examining the high-quality head torch I had given him.

"That's my job."

I helped them adjust their rucksacks and showed them how to distribute the weight.

"Fill your water bottles. Once that's done, we'll set off."

While they fumbled with bottles and hydration bladders, I stepped away and studied the sky. Dark clouds were gathering above the western ridge. They were not immediately threatening, but they concerned me. The forecast had mentioned the possibility of afternoon showers; those clouds suggested something more substantial.

I decided not to mention it yet. There was no point alarming them while we still had ample time to reach shelter.

"All set," I called, shouldering my rucksack. "Let's go. Stay together, pace yourselves and say something if you need a rest."

I deliberately chose an easy pace as we left the car park and followed the forestry-track entrance into the trees.

Within the first kilometre, I could tell that these men seldom exercised outside climate-controlled gyms. Oliver adjusted his shoulder straps every few minutes. Rupert's cautious steps showed that he was preoccupied with the possibility of turning an ankle. Miles stopped repeatedly to photograph ordinary lichen, Scots pine cones and waymarker posts. Alistair checked his satellite phone at every slight rise in the ground, while Graham's breathing was already laboured.

"The trees open out beyond this bend," I told them, pointing ahead. "You'll be able to see the floor of the glen and the ridge we're following tomorrow."

"How much farther to the first proper stop?" Oliver asked, sounding strained despite our gentle pace.

"We've covered about a kilometre and a quarter. The planned break is at three kilometres, but we can stop earlier if necessary."

"I'm fine," Oliver insisted, although his reddening face suggested otherwise.

I had guided worse groups. There had been stag parties arriving hungover, corporate retreats where half the participants were actively trying to undermine the other half, and families whose teenagers refused to look up from their phones. These five were at least enthusiastic about the expedition, even if they were woefully unprepared for it.

The woodland thickened around us. Ancient Scots pine and birch gave way in places to dense planted spruce, with juniper crowding the more open ground. Sunlight shifted across the forest floor through the branches overhead. I pointed out fresh red-deer slots, a buzzard circling above the glen and the distant ridges we would approach over the following days.

By midday we had covered a little over six kilometres. I called a lunch break beside a burn and helped everyone find dry places to sit and remove their rucksacks. They unpacked rolls, oatcakes and flasks of soup prepared by the upmarket hotel where they had spent the previous night.

While they ate, I walked a short distance away and checked the sky again. The clouds had grown darker and were moving towards us. The wind had strengthened too, bending the tops of the taller trees. Twenty years in the Highlands had taught me to trust that combination. Rain would reach us well before nightfall.

I glanced back at the group. They were engrossed in a loud debate about private equity and fintech investments. I decided we would need to make better progress after lunch.

"We'll leave in fifteen minutes," I announced as I returned. "The next section has less cover, so we'll want to move efficiently."

"Why the rush?" Graham asked between bites of a thick roast-beef roll. "The brochure described this as a leisurely expedition."

"I'm being cautious with the daylight," I said, without mentioning the approaching front. "It's better to have time in hand at camp than to pitch in a hurry."

We resumed with slightly more purpose. I kept them moving through gentle but persistent encouragement, pointing out features of the glen to distract them from their growing fatigue.

The track narrowed into a climbing path. Laboured breathing followed me as we worked through a series of zigzags towards higher ground. By mid-afternoon the wind had become strong enough to tug at our clothing, and I could smell rain in it.

We were still about a kilometre and a half short of my planned camp when I spotted a suitable alternative at roughly the 8.5-kilometre point: a fairly level patch among the trees, with water nearby and a natural windbreak formed by a rocky outcrop.

"We'll camp here," I announced, stopping in the clearing.

"Already?" Miles checked his fitness tracker. "We've only done eight and a half kilometres. The itinerary said ten."

"This is the better site in these conditions," I said, indicating the protection around us. "Level ground, a reliable water source and shelter from the prevailing wind."

A distant rumble of thunder underlined my point. The clients exchanged uneasy looks.

"Right, let's get the tents up," I said, lowering my rucksack and spreading a groundsheet. "I'll demonstrate with mine, then help each of you."

I pitched my two-person tent quickly, explaining each stage as I fitted the poles, secured the flysheet and tensioned the guy lines. The five men watched with varying degrees of comprehension.

"Now yours," I said, moving towards Oliver.

The following hour tested my patience. Oliver repeatedly tried to fit poles into the wrong sleeves. Rupert treated assembling his tent like a surgical procedure, analysing each step until I gently hurried him along. Miles kept interrupting himself to film the process. Alistair attempted to make business calls on his satellite phone while driving pegs one-handed. Graham became frustrated within minutes and eventually stood aside while I did most of the work under his supervision.

By the time all six tents were standing, the first heavy drops had begun to fall. There was one tent for me and one for each client. I showed the men how to stow their equipment and placed our sealed food bags in wildlife-proof storage well away from the tents, where they would be less likely to attract pine martens, foxes or rodents.

"We'll cook beneath that overhang," I said, pointing to the sheltered rock at the edge of the camp. "The worst of this should pass by morning."

The rain intensified as darkness approached. In the protected space below the rock, I set up the stove and prepared venison and barley stew. My clients had apparently expected nothing but freeze-dried packets and seemed surprised by the result.

"This is actually good," Alistair admitted between spoonfuls.

"Twenty years of practice," I replied, stirring the pot. "You learn what travels well."

After dinner, with everyone huddled beneath the overhang, I briefed them on the next day's route and the wildlife we might encounter. Rain drummed steadily through the canopy and occasionally struck the rock in heavy splashes.

"Any questions before we turn in?" I asked as I packed away the cleaned cooking equipment.

Oliver peered into the darkness beyond our small circle of light.

"Are we safe here? From foxes and things?"

"We've taken the proper precautions. The food is sealed and stored away from the tents, and I'm a light sleeper. Keep all snacks out of your tents and there shouldn't be a problem."

As they retired, I made a final circuit of the camp. I checked the food storage and made sure every flysheet was properly tensioned against the wind. The storm had settled in, but our position was sound. Shallow drainage channels would take water away from the tents, and the trees and rock broke the worst of the gusts.

At the edge of the camp I paused and listened through the rainfall: branches creaking, water pattering on leaves and the occasional call of a night bird. This was where I felt most at home, even with responsibility for five inexperienced clients weighing on me.

Once everything was secure, I crawled into my tent and spread my sleeping bag over the insulated mat. Through the fabric I could hear Oliver fumbling with his head torch, Miles's camera beeping as he reviewed the day's photographs, and Rupert asking Alistair about the correct use of a sleeping-bag liner.

I zipped myself into the bag and listened to the rain, mentally reviewing the following day's route and considering alternatives if the weather failed to clear. Experience had taught me always to keep contingency plans ready, particularly with a group this green.

As I drifted towards sleep, I had no idea what the expedition would bring. I was still confident that I could manage whatever difficulties arose. That was, after all, what they were paying me GBP 15,000 to do.

The first day had gone about as well as I had expected, which was to say not especially well. The second followed much the same pattern.

By midday Oliver was limping. His expensive new walking boots had proved a poor match for feet that had never worn them properly before the trip.

"Callum, have you got any more of those plasters?" he asked as he lowered himself on to a flat rock near our lunch stop. He winced as he removed his right boot.

I opened my first-aid kit.

"Use the Compeed blister dressings. They'll hold better than ordinary plasters."

He struggled with the packet, clearly unfamiliar with even basic first aid. I knelt to help and found three angry blisters on his heel and the side of his foot.

"This is why we break in new boots before a trip like this," I said, keeping my tone neutral while I applied the dressings.

Oliver nodded sheepishly.

"The salesman said they would be comfortable straight away."

I suppressed a remark about trusting outdoor-equipment salesmen working on commission. Once his foot was protected, I checked on the others.

Rupert was about twenty metres away at the edge of a burn, concentrating on his water filter with the intensity of a man solving an engineering problem. He had assembled it backwards.

"Need a hand?" I asked as I approached, taking care not to startle him.

"I followed the instructions exactly," he said, unable to hide his frustration. "The diagram shows this piece connecting to the valve, but it isn't working."

I gently took the filter from him.

"You've reversed the intake and outlet. Easy mistake."

I reassembled it and demonstrated the correct method.

"Try now."

Rupert flushed slightly as he filled his water bottle.

"Thanks. I should have worked that out."

Miles wandered over with his camera in hand.

"Callum, can you get a photograph of me filtering water? My followers will love some authentic Highland survival."

I stepped aside as he handed his mobile to Rupert and posed theatrically beside the burn, lowering the filter with exaggerated care. I had already explained at least three times that there was no mobile signal, but he remained determined to document everything for a mass upload when we returned to civilisation.

Alistair sat apart from the group, picking at his lunch with obvious distaste.

"Callum," he called, "these dehydrated meals are barely edible. Couldn't we have packed something with genuine nutritional value?"

"They contain the calories and nutrients you need for this sort of activity," I replied evenly. "They're also light, which matters when you carry everything on your back."

Alistair muttered that he had paid enough to expect better accommodation. I had heard variations of the same complaint a dozen times since we set out.

Graham approached with a map in his hand and the familiar expression of a man convinced he knew better.

"Callum, I've been studying the route. If we cut through this glen rather than following the ridge, we could save at least three kilometres tomorrow."

I looked at the line beneath his finger.

"That ground floods at this time of year. It seems shorter on the map, but we'd lose hours in bog and swollen burns, assuming we got through at all. The ridge is safer and, in practice, quicker."

Graham remained unconvinced but folded the map with a shrug.

"If you say so."

I knew the pattern. These were senior executives accustomed to making decisions and having their opinions carry more weight than anyone else's. Out here their professional expertise meant little, but men who defined themselves through authority rarely accepted that easily.

By the time we established our second camp that evening, I was mentally exhausted from managing their egos and expectations. I nevertheless kept my expression composed as I helped with the tents. Rupert overthought each stage and repeatedly consulted the instructions. Miles photographed his half-assembled shelter instead of completing it. Alistair tried to conduct business over the unreliable satellite connection and left his kit scattered around his pitch. Graham insisted he knew what he was doing until his tent collapsed for the third time, when he finally accepted my help.

As darkness fell, I prepared a simple lentil hotpot. Even Alistair admitted it was decent. Afterwards I secured our food away from the tents, checked that everyone had what they needed and answered questions about the next day's route.

Physical fatigue had joined the mental exhaustion by the time I climbed into my own tent. Sleep came quickly, as it usually did after a long day in the hills.

It did not last.

I woke abruptly in the darkness, my body tense before my mind understood why.

Music was moving through the trees, if music was the right word. In twenty years of guiding, I had never heard anything like it.

The melody shifted in ways that felt fundamentally wrong. Notes bent through patterns that made my skin crawl. The sound seemed ancient and wholly alien, as though it predated human music and had never been intended for human ears.

I sat upright in my sleeping bag, suddenly alert. Every hair on my arms lifted as the sound echoed through the woodland. It came from everywhere and nowhere, impossible to locate.

I took my head torch and opened the tent as quietly as I could. Outside, in the cold night air, the notes rose and fell in sequences that seemed to obey a system of harmony from somewhere beyond the world I knew. No human instrument could have produced them. I was certain of that.

I had heard strange noises in the Highlands: the bark of foxes carrying oddly through a glen, wind setting up a low vibration in cracks between rocks, and insects producing a chorus that sounded almost mechanical. This was different.

This was wrong.

I turned slowly, trying to identify a direction. The camp remained still. My clients appeared to be asleep through the otherworldly performance. The music seemed strongest beyond the clearing, deeper among the trees.

I took several steps towards the edge of the woodland and considered investigating. Twenty years of experience told me not to walk into unfamiliar ground at night. The same experience told me that the sound was not natural and could not be explained by anything I knew about these hills.

Before I decided, the music began to fade. It did not end like a piece performed by a musician. It sounded as if it were being drawn away, the notes stretching thinner and thinner until they vanished.

Within moments, ordinary night sounds returned: the faint movement of leaves, a bird calling somewhere in the darkness and the burn flowing beyond the camp.

I remained motionless for several minutes, listening for the music to return. It did not. Eventually the cold forced me back into my tent, but sleep came slowly. I lay awake for what felt like hours, replaying the impossible melody and trying to make sense of it.

Morning brought welcome normality. Birds called in the trees, sunlight filtered between the branches and my clients began stirring in their tents.

I was already heating water for instant coffee when Oliver emerged, rumpled and tired.

"Did you hear that strange noise last night?" he asked, accepting the mug I offered.

My stomach tightened. I had not imagined it.

"What did it sound like to you?" I asked carefully.

Oliver frowned and blew across his coffee.

"I don't know. A bit like music, but not quite. It woke me for a while. I assumed it was the wind."

I kept my expression neutral.

"That can happen in this area. Wind passes through cracks in the rocks to the east and produces unusual sounds."

"Right," Oliver said, apparently satisfied. "It was almost like singing. Very odd."

"Nature can play tricks on your ears, particularly at night."

I turned to check the porridge, although I did not believe my own explanation for a second. Wind in rock could whistle, hum and create harmonics that sounded faintly musical. What I had heard had been complex, structured and intentional. It was not random noise shaped by the land.

It was something else.

But what could I tell them? That unexplained music had sounded through the woods? That something beyond my understanding might be waiting in the darkness? These men were already struggling with the routine demands of hillwalking. Giving them a supernatural fear would only make them harder to manage.

As the others emerged and gathered for breakfast, I kept the conversation on practical matters: the day's route, the weather and the possibility of seeing ptarmigan or mountain hare higher up. Nobody else mentioned the music, and I did not raise it.

While we struck camp, however, I found myself studying the forest more closely than usual, searching for a sign or an explanation. There was nothing visibly wrong. Only trees, stone and the ordinary features of a remote Cairngorm glen I thought I understood.

We shouldered our rucksacks and set off. My clients settled into their familiar habits: Oliver adjusting his straps every few minutes, Rupert watching every footfall, Miles stopping for photographs, Alistair checking the satellite phone and Graham breathing heavily while refusing to admit that he needed a rest.

I maintained an outward calm, but my thoughts kept returning to the impossible notes that had filled the second night of our trek. In twenty years I had never experienced anything like them, and despite what I had told Oliver, I possessed no rational explanation.

Later that day, I stopped when I noticed Miles crouching at the edge of a clearing.

The group had spread out across the open ground after hours beneath the trees. Miles was bent over something, his whole posture alive with excitement.

"Callum, come and see this."

He waved me over. I crossed the long grass towards him, the midday sun warm against the back of my neck.

"Look," he said, holding up a perfectly round stone approximately the size of a cricket ball.

I crouched beside him, and he placed it in my outstretched hand.

The instant it touched my skin, I knew that something was wrong.

The stone was unnaturally smooth, unlike anything I had encountered in two decades outdoors. Its surface held no flaw, chip or scratch, nothing to suggest that it had been shaped by natural forces or lain exposed in the glen.

"Feel how perfectly round it is," Miles said, his eyes bright.

What disturbed me even more was the faint vibration. At first I mistook it for my pulse, but the rhythm did not match. The object itself appeared to hum with energy, sending an unpleasant tingling through my palm.

"Where exactly did you find it?" I asked, struggling to keep my voice level against the urge to drop it.

Miles pointed to a shallow depression a couple of metres away.

"It was sitting there as if someone had placed it. Strange, isn't it?"

I returned the stone and wiped my hand against my trousers. The tingling remained.

"Put it back where you found it."

Miles laughed.

"Are you serious? This is extraordinary."

"We're in a protected part of the Cairngorms National Park, and this is a sensitive conservation site. Removing objects could lead to fines or prosecution."

That was true, but it was not my principal concern. Something about the stone felt deeply wrong in a way I could not express. The instinct that had saved me from bad weather, unstable ground and poor decisions throughout my career was screaming at me to leave it alone.

"Who would ever know?" Miles said, rolling it between his hands. "It's only an interesting rock."

The others had gathered around us, drawn by his excitement.

"What have you found?" Oliver asked, adjusting his expensive sunglasses.

"Some sort of stone artefact," Miles said before I could answer. "Perfectly round. It could be valuable."

"I strongly recommend that you leave it here," I said more firmly. "Apart from the legal issue, we don't know what it is or where it came from."

Alistair gave a dismissive snort.

"It's a stone, Callum. Hardly a mystery."

But it was. The flawless surface and the vibration could not be dismissed as the work of water polishing an ordinary river stone. This was something else.

"Miles, listen to me," I said. "My responsibility is to keep all of you safe. Part of that is respecting protected ground. That object belongs here, not on a shelf in somebody's London house."

Miles watched me for a long moment, then smiled and shrugged.

"I hear you, but I'm keeping it. It will make a brilliant souvenir."

Before I could object again, he put the stone in the top compartment of his rucksack.

"We need to keep moving if we're to reach camp in good time," I said, knowing that I had lost the argument for now.

As we continued, I kept glancing at Miles's rucksack. I could not shake my unease. The clients talked about London property, fintech investments and second homes, but my thoughts remained fixed on the stone. In all my years as a guide, I had never felt such immediate revulsion towards an object.

We reached the next camp with about an hour of daylight remaining. It was a small plateau protected by Scots pines, with a clear burn nearby. I supervised the tents with only half my attention, watching Miles more closely than usual. He seemed normal enough, joking with the others and complaining about the lack of mobile signal.

After dinner, darkness settled over the camp and everyone withdrew to his tent. I made my usual circuit, secured the food and eventually climbed into my sleeping bag.

The day's exertion should have pulled me immediately into sleep, but I lay awake and listened.

The music began so quietly that I thought I might be imagining it. Then it grew stronger, clearer and more defined than it had been the previous night. The same impossible notes bent in ways no music should. The same sense of immense age raised the hairs on my arms.

This time the sound seemed to rise from the earth, vibrating through the ground beneath my sleeping mat.

I remained completely still and listened to the unearthly melody. It was not merely louder. It felt closer and more insistent, as if it were attempting to communicate.

The notes twisted through patterns my mind could not follow, producing harmonies that should not have been possible.

Movement came from the tent beside mine - Miles's tent. A sleeping bag rustled, followed by muttering. At first I thought he was speaking to one of the others, but the cadence was wrong. It sounded like someone talking in his sleep.

I strained to distinguish words but heard nothing coherent, only low murmurs interrupted by sharp breaths. The music strengthened with each sound Miles made, as if answering him.

The connection came to me with sudden, dreadful clarity.

The stone he had insisted on keeping was linked to the music. The timing was too exact to dismiss. The music had come before we found it, but after Miles removed the object from its hollow, the sound had become louder and closer. There was also the vibration in my hand and the stone's impossible perfection.

I wanted to go to Miles, take the thing and hurl it into the darkness. Yet a deep instinctive caution held me inside my sleeping bag. It was not quite fear. It was the knowledge that acting without understanding might make matters worse.

The music continued to weave through the night, following patterns my brain could not properly process. Miles's muttering grew louder. I began to catch fragments, not words but sounds that imitated the impossible melody around us.

His voice rose and fell with the music as though he were trying to sing in his sleep.

I pressed my palms over my ears. It made no difference. The sound did not appear to be travelling solely through the air. It resonated inside my skull, reaching me by some route I could not block.

In twenty years among the mountains, I had heard wind groaning through stone, distant animal cries distorted by the shape of a glen and the low-frequency rumble of avalanches far beyond sight. None of those sounds resembled this.

This was structured. Intentional.

The rational part of my mind searched desperately for an explanation. Altitude-related hallucination was unlikely; we were nowhere near high enough, and I had none of the other symptoms. Carbon monoxide from a faulty stove made no sense in open air and did not fit what was happening. Group hysteria was impossible if most of the group remained asleep.

That left the stone.

Miles's muttering stopped abruptly, and the music paused with him. The silence lasted only a few seconds. Then both resumed in perfect synchronisation.

Whatever connection existed between Miles and the object was becoming stronger.

I lay awake for what felt like hours, listening to the interplay between the unearthly music and Miles's unconscious responses. Eventually the sounds faded. The melody thinned until it vanished, leaving only wind through pine needles, the occasional call of an owl and the burn moving over stone. Miles became silent at the same moment.

I waited another half-hour to make certain it had ended, then allowed myself to relax enough to drift towards sleep.

My final conscious thought was a decision: in the morning I would persuade Miles to leave the stone behind, whatever it took.

Daylight arrived with painful brightness. I crawled out, stiff and unrested, to find the others already stirring. Oliver stood beside the cold fire pit, attempting to light the stove for coffee. Rupert was reorganising his excessive first-aid supplies for the third time. Alistair and Graham sat on logs comparing the performance of their satellite devices.

Miles emerged last and looked surprisingly refreshed. The shadows that had lain beneath his eyes the previous day had vanished, and he moved with more energy than he had shown since the start of the trek.

"Morning, Callum," he said cheerfully. "Beautiful day, isn't it?"

I studied his face for any sign that he remembered the music or his muttering. There was nothing, only his usual self-satisfied expression.

"Sleep well?" I asked, handing him a mug of instant coffee.

"Like a rock," he said, laughing at his own joke. "Speaking of which..."

He reached into his rucksack and took out the stone.

In daylight it appeared even less natural. It was perfectly spherical, with a surface so smooth it might have been polished. Its colour was hard to define, somewhere between deep grey and black, but subtly changing when the light struck it from different angles.

"Still think I should have left it?" Miles asked, holding it up. "It looks even better this morning."

The others gathered to examine it. I watched their faces for any indication that they had heard the night's music, but saw only ordinary curiosity.

"It is unusual," I admitted. "My recommendation stands. Leave it here."

"Why are you so agitated about a stone?" Graham asked, frowning.

I chose my words carefully. These were wealthy, successful men accustomed to getting their way. If I told them that an impossible melody had filled the camp while Miles sang back to it in his sleep, my credibility would disappear.

"I've seen what happens when people remove things from protected sites," I said. "There can be substantial fines and prosecution even for taking an ordinary natural object. If this has archaeological significance, the consequences could be much more serious."

Miles rolled the stone between his palms, unconcerned.

"I'll take my chances."

"Did you notice anything strange last night?" I asked. "Any unusual sounds?"

He looked at me blankly.

"Such as?"

"Music, perhaps."

The others exchanged looks.

"Music?" Oliver laughed. "Out here?"

"I slept like the dead," Alistair said. "I didn't hear a thing."

Miles shrugged.

"Nor did I. Why? Did you hear something?"

He remembered neither the music nor his sleep-talking. That troubled me almost as much as the sounds themselves.

"Only something odd in the wind," I said vaguely. "It was probably nothing."

Miles returned the stone to the top of his rucksack, and frustration surged through me. As their guide I had authority over route and safety, but without evidence of immediate danger, forcing him to abandon his souvenir would appear arbitrary. They were paying clients, and however much I disliked it, guiding remained a service profession.

As we broke camp, I watched Miles closely. He seemed ordinary apart from his unusual energy. Throughout the morning I saw him reach into the top of his rucksack several times to touch the stone, almost unconsciously, like a man checking that his wallet or keys were still there.

I wanted to believe the previous night had been an isolated occurrence, but I knew it had not. The music would return. It would probably be stronger, and somehow I had to make Miles surrender the stone before we discovered what it truly was.

Over the next few days, I kept him under close observation. His behaviour began to change in small ways, the sort of changes that most people would have missed.

But after 20 years of watching clients in the hills, I had learnt to recognise the warning signs. During our morning walk, Miles Redmond lagged behind the group, one hand always inside the top pocket of his rucksack, where he had stowed the stone. Every 15 minutes or so, he stopped altogether, took it out and stared at it before tucking it away again.

"Everything all right back there?" I called after the third time.

"Yes. Just checking something," he answered, quickening his pace to catch up.

By lunch, the pattern was impossible to miss. While the others unpacked flapjacks and cereal bars on a broad shelf of granite overlooking the glen, Miles sat apart with the stone resting in his palm. He stroked its surface with his thumb in slow circles.

"That's quite a stone you found," Oliver Grant said, trying to make conversation.

Miles drew it closer to his chest. "It's warm," he said without looking up. "Can you believe that? It stays warm all the time."

"Probably just retaining your body heat," Dr Alistair Khan suggested between bites of a cereal bar.

"No," Miles insisted. "It generates its own heat. Here, feel it."

He held it out reluctantly. Alistair reached across and touched it for a moment.

"Feels like an ordinary stone to me," he said with a shrug.

I watched disappointment cross Miles's face before his expression hardened into resolve.

"You just don't understand it," he muttered, turning away and continuing to stroke the stone.

That afternoon, the path followed a high ridge with wide views into the glen below. The weather remained settled: clear skies, mild air and a light breeze, ideal hillwalking conditions. Miles seemed oblivious to the landscape. All his attention had turned inwards.

During our brief rests, while the others took photographs or checked Alistair's satellite phone for messages, Miles wandered several metres away, held the stone at eye level and spoke to it in a low voice. The first time I caught him doing it, I approached without haste.

"Found anything interesting about that stone?" I asked, keeping my tone light.

Miles started and nearly dropped it before closing both hands around it.

"It has patterns," he said. "If you look closely enough, you can see them moving."

I examined the stone. In daylight it remained unnaturally perfect, a sphere approximately the size of a cricket ball, so smooth that it seemed machined rather than shaped by water or ice. Its colour shifted subtly between deep grey and black as the light changed, but I could see no patterns.

"Perhaps you should drink some water," I suggested, offering him my spare bottle. "Dehydration can make you see things that aren't there, particularly after a long day on the hill."

His face darkened.

"I'm not dehydrated," he snapped, thrusting the stone into his pocket. "And I'm not seeing things."

I backed away, but I continued to watch him.

That evening we camped in a small clearing among Scots pine and birch. Miles whispered to the stone whenever he thought no one was looking. At dinner he barely touched the lentil hotpot, keeping one hand inside his jacket pocket, where I knew he was holding it.

The other clients had noticed as well. I saw Graham Whitaker and Rupert Hargreaves exchange uneasy glances when Miles answered Oliver's question about his commercial property business with a remark about ancient woodland.

"The trees remember everything," Miles said, his gaze unfocused. "They've stood here for centuries, listening."

"Some of these Scots pines are certainly old," I said, trying to make the remark sound ordinary. "Parts of the Highland ecosystem have endured in one form or another for thousands of years."

Miles looked at me with sudden intensity. "Exactly. They've watched them come and go."

"Watched whom?" Rupert asked.

Miles merely smiled and resumed running his fingers over the stone in his pocket.

After dinner, while the others prepared their tents for the night, I took Miles aside.

"Look, Miles, I think you may be unwell," I said gently. "Exhaustion, disrupted sleep and the conditions out here can affect people in strange ways. Confusion, fixation, even mild hallucinations. There's nothing embarrassing about it, but I need to monitor you."

His response was immediate and defensive.

"There's nothing wrong with me," he hissed, stepping back. "You're only trying to take it from me."

"Take what?"

"The stone. You want it because you know it's special."

I raised my hands to calm him. "I don't want your stone, Miles. I'm concerned about your health, that's all."

"I'm fine," he insisted, loudly enough for Oliver to glance over from his tent. "Better than fine. I'm understanding things I never understood before."

I decided not to press him. Pushing harder would only feed his paranoia, and we were still deep in a protected part of the Cairngorms, days from the end of our planned route. I would watch him carefully and reassess him in the morning.

That night I lay awake, listening to the familiar sounds beyond the fabric of my tent: small nocturnal creatures moving through the undergrowth, wind whispering through pine needles and, once, the distant call of an owl. The impossible music that had first disturbed us on the previous night did not return, but I remained tense, expecting it at any moment.

At about two in the morning, I heard the distinctive rasp of a tent zip. Quiet footsteps followed, moving away from camp. I waited a minute, then silently opened my own tent and stepped into the cold air.

The moon was nearly full. Its light was strong enough for me to make out Miles roughly 30 metres from camp. He sat cross-legged on a flat rock with his back to me, his head bowed over something held in his hands.

The stone.

I approached slowly, making just enough noise to avoid startling him. When I was about three metres away, I heard his voice, soft but clear in the night.

"Yes, I understand," he was saying. "They were here first, long before us."

I cleared my throat. "Miles."

He turned. In the moonlight his face looked altered, relaxed yet strangely vacant. His pupils were dilated despite the brightness, and his eyes reflected the moon with an unnatural gleam.

"Callum," he said in an oddly formal voice. "Come and listen. It's singing to me."

I moved closer, fighting an instinct to retreat. "What's singing?"

"The stone." He raised it towards me. "It sings when everyone else is asleep. It tells me things."

I crouched beside him and saw that the stone was trembling in his palm. The vibration was stronger than it had been at the archaeological site, no longer a faint sensation but a visible shudder.

"What sort of things does it tell you?" I asked carefully.

His face brightened with childlike wonder. "About the old ones who lived here before human beings. They understood the music of the earth in ways we've forgotten."

He leaned closer and whispered as if sharing a confidence.

"They're still here, you know. Waiting beneath the mountains."

A chill passed up my spine that had nothing to do with the cold.

"Miles, I think you may be hallucinating. Exhaustion and broken sleep can do that, particularly in an unfamiliar place."

He laughed, but it was a hollow sound, nothing like his usual booming chuckle.

"That's what they said people would think. That's why they speak to only one person at a time." He drew the stone against his chest. "They chose me, Callum. They chose me to hear their message."

I tried another approach. "What if you put the stone away until morning? Get some rest, then look at it again with fresh eyes."

His expression changed at once. His face hardened and he clutched the stone more tightly.

"You don't believe me. You think I'm mad."

"I don't think you're mad," I said truthfully. "I think something strange is happening, and we need to be careful."

"The stone is mine," he said. "I found it, and it chose me."

I recognised the signs of a developing psychological crisis: paranoia, grandiose beliefs and an intense attachment to an inanimate object to which he attributed special powers. In Aviemore I could have called for professional help. Out here, far from any road and without a mobile signal, my choices were limited.

"Let's at least go back to camp," I said. "It's cold out here."

After several minutes of gentle persuasion, Miles agreed. He returned to his tent with the stone still clenched in his hand. I watched him close the zip, then went back to my own tent with my thoughts racing.

For hours I listened for any sign of him moving again. I knew I was facing an impossible decision. If his condition worsened, I would have to evacuate the group. It would end a GBP 15,000 bespoke expedition and earn me the resentment of the other clients. If I did nothing and Miles came to harm, the responsibility would be mine.

Eventually I slipped into an uneasy sleep. Miles's dilated pupils and the trembling stone followed me into troubled dreams.

I woke feeling as though I had not slept at all, with the weight of those choices pressing down on me. I had to keep everyone safe, yet I had no idea how to protect Miles from what was happening to him, or from himself.

Then a symphony erupted inside my skull.

The music had returned, louder and more immediate than before, so impossibly present that I could not pretend it came from anywhere ordinary. Notes bent and twisted beyond any musical logic, joining in harmonies that should not have been possible and yet somehow were.

I sat bolt upright in my sleeping bag. My breath clouded the cold air inside the tent. This was not merely louder than the first night's music. It had changed. There was a desperate urgency in it, as though it were calling to someone or commanding them.

Miles.

I scrambled out of the sleeping bag and dragged on my walking boots without lacing them properly. The temperature had fallen sharply, and a thin covering of snow lay across the ground. I opened the tent with fingers already stiff from the cold and stepped outside.

The camp was still. All six tents remained standing: mine, the four occupied by the sleeping clients and Miles's tent, whose entrance hung open and stirred in the breeze.

I crossed to it in three strides and thrust my head inside. The beam of my torch showed an empty sleeping bag still bearing the shallow impression of his body.

My stomach dropped. I was responsible for all five men, and Miles was somewhere beyond the camp, following that impossible music.

"Damn it," I muttered.

Fresh footprints led from his tent into the trees, a single line pressed into the light snow. I switched on my head torch and followed without hesitation.

The footprints moved with purpose. This was not the meandering route of a sleepwalker but the direct progress of someone answering a summons. They led into the densest part of the woodland, where Scots pine and planted spruce crowded together and shut out most of the moonlight.

I moved as quickly as I could without losing the trail, my breath streaming white ahead of me. The music strengthened with every step, confirming that I was moving towards its source.

After perhaps ten minutes, the footprints became uneven and erratic, as if Miles had begun to stumble or lose coordination. The trees opened ahead into a small clearing washed in moonlight.

Miles stood at its centre.

He faced away from me, utterly still, his posture unnaturally rigid. Even from six metres away I could see that something was terribly wrong. His arms were extended before him, holding an object that shook so violently it blurred in the moonlight.

The stone.

It vibrated with enough force to send tremors through his arms and make his whole body quiver. Dark liquid ran down both sides of his neck, black beneath the moon but unmistakably blood. It streamed from his ears and soaked the collar of his waterproof jacket.

"Miles," I called.

My voice sounded thin against the overwhelming music. He did not answer or move. He only swayed almost imperceptibly to rhythms that filled my head with dreadful clarity.

The music was beautiful in a way that made my skin crawl. Its complex patterns seemed to contain knowledge, ancient and appalling, and filled me at once with wonder and bone-deep terror. It was like glimpsing something the human mind had never been made to comprehend.

I approached slowly and called his name again, louder.

"Miles, can you hear me?"

There was no response. Blood continued to trickle from his ears, and whatever was happening was plainly worsening by the second.

When I reached him and moved round to see his face, I had to suppress a gasp. His eyes had rolled upwards until only the whites showed. His mouth hung slightly open, and his expression was one of rapture despite the blood dripping on to his shoulders.

The stone in his hands vibrated with impossible speed, its surface shifting between deep grey and absolute black faster than my eyes could follow. It was no longer merely shaking. It seemed to pulse, as though alive.

A terrified inference seized me. The music might be physically injuring him. Human hearing was not made to receive those impossible harmonies, and Miles had listened night after night, each encounter longer and more intense than the one before. I could not know the mechanism, but I knew I had to stop it.

Acting on instinct, I reached out and tore the stone from his hands.

His fingers opened without resistance. The instant the stone left him, his body went limp, and I lunged forwards to prevent him falling face first into the snow.

The stone was unnaturally heavy in my palm. For one appalling moment, the music rose to an unbearable crescendo, as if protesting at being taken from its chosen listener. Vibrations travelled through my arm and chest, rattling my teeth and blurring my vision.

Then the music stopped.

The silence was so sudden that my ears rang with its absence. One moment the impossible harmonies had filled my skull; the next there was a vacuum so complete that I wondered if I, too, had lost my hearing.

I stood frozen, supporting Miles's weight while the stone lay lifeless in my hand.

"Miles," I called.

My voice sounded distant and wrong after that otherworldly symphony. He did not respond. His head lolled backwards, his face slack and pale. Blood still marked both ears.

I lowered him carefully on to the snow and pressed two fingers to his neck, holding my breath until I found a steady pulse. His breathing was shallow but regular.

The stone remained inert. I turned it over, studying its perfect spherical form. Moments earlier it had throbbed with impossible energy. Now it felt like an ordinary piece of rock: cold, smooth and dead.

I slipped it into my jacket pocket and returned my attention to Miles.

"Miles, can you hear me?"

I patted his cheek, first gently and then more firmly. Nothing. I checked his pupils with my torch. They contracted normally, which offered some reassurance, but he remained unresponsive, his body limp and heavy.

The bleeding had stopped, leaving dark tracks down his neck and inside his collar. Returning him to camp would be difficult. He was a large man, and the snow had made the woodland floor treacherous.

I unfolded the emergency bivvy from my rucksack, rolled Miles carefully on to it and wrapped him against the cold. Using the reinforced edges as an improvised hauling sheet, I dragged him over the smoother ground, lifting his shoulders across roots and rocks where necessary. The clearing was only a few hundred metres from camp, but the return took far longer than the journey out.

I stopped repeatedly to check his airway, breathing and pulse, and twice nearly lost my footing on the snowy ground. He remained unconscious, but his breathing stayed steady.

When the trees finally opened and the tents came into view, relief washed through me. The camp was undisturbed. Five other tents stood dark in the snow, Miles's entrance still open exactly as I had left it. The four remaining clients slept on, unaware of the crisis.

I hauled Miles to his tent, manoeuvred him inside and laid him on his sleeping bag. I removed his boots and wet outer layers, then zipped him into the bag to keep him warm. The blood around his ears and neck had begun to dry, but I used water from my bottle and a sterile dressing from the first-aid kit to clean what I could without probing either ear.

I made a monitoring position immediately outside the tent, laying down my sleeping mat and bag so I could remain beside him. I placed the first-aid kit, satellite messenger and personal locator beacon within reach.

Then I began a long vigil, checking Miles's vital signs every 20 minutes. His pulse remained steady and his breathing never faltered, but he did not wake, stir or show any sign of returning to consciousness.

The stone was no longer beside him. It stayed in my zipped jacket pocket, cold and silent against my thigh.

The night seemed endless. I pinched my legs and splashed cold water on my face whenever my eyes began to close. The temperature continued to fall. I pulled my jacket tighter and watched my breath cloud in the beam of my head torch.

By the time the eastern sky began to pale, I had made my decision. Miles needed urgent hospital treatment. The expedition was over.

I knew there would be resistance. These men had paid GBP 15,000 for an exclusive six-day trek, but Miles's condition allowed no debate. I waited until I saw movement in the other tents before calling everyone together.

Oliver emerged first, fastening his jacket against the morning cold.

"What happened?" he asked when he saw me outside Miles's tent. "And why is it so bloody cold?"

"The temperature dropped overnight," I said. "Miles is ill. I need to speak to everyone."

The others appeared one by one. Alistair checked his satellite phone as usual. Rupert rolled his sleeping mat with meticulous care. Graham complained under his breath about the cold.

"Listen," I said when they had gathered. "Miles is unconscious. He left camp during the night, and I found him collapsed in the woodland. We're ending the expedition and arranging an emergency evacuation now."

Their reactions came quickly.

"Unconscious?" Rupert asked, his face creased with concern. "From what?"

"What about the rest of the route?" Graham demanded. "I cleared my diary for this."

"Is he breathing?" Oliver asked, looking towards the tent.

"Yes. His pulse and breathing are stable, but he needs urgent medical attention. I'm contacting Police Scotland and requesting mountain rescue as soon as we have enough light for a safe response."

Alistair stepped forwards, his expression calculating.

"I paid GBP 15,000 for this, Callum. Surely we can divide the group. You take Miles out and the rest of us continue along the planned route."

I shook my head. "No. I cannot leave four clients here without a qualified guide, and Miles needs help immediately. This isn't open to discussion."

"What exactly is wrong with him?" Rupert asked.

I hesitated, unwilling to mention either the stone or the music.

"I don't know. It may be a seizure or another acute neurological problem. He's unresponsive, although his vital signs are stable."

"Can we see him?" Oliver asked.

"Briefly. Then I need you to pack and follow my instructions. The sooner we're ready, the easier the rescue will be."

I opened the tent and allowed them to look inside. Miles lay motionless in his sleeping bag, his face pale. Despite my efforts, dried blood remained visible around his ears.

"Jesus," Graham muttered. "What happened to his ears?"

"I don't know," I said, truthfully. "That's why he needs a hospital."

The sight of him silenced every further complaint. The men returned to their tents and began packing with uncharacteristic efficiency.

I took the satellite messenger and personal locator beacon a short distance from camp. I activated the emergency signal, then used the satellite phone to call 999, asked for Police and requested mountain rescue. Police Scotland took our exact Ordnance Survey grid reference, Miles's condition and details of the surrounding terrain. They confirmed that the volunteer mountain rescue team was being mobilised and that a Coastguard rescue helicopter had been requested.

I described a more open area roughly 400 metres away which might permit a landing in suitable conditions or provide a safer winching point. I was warned that weather, aircraft availability and our remoteness could mean a wait of up to six hours. The four clients were to remain at camp with shelter, food and communications until a replacement qualified guide and a mountain rescue team member reached them.

When I returned, most of their equipment had been packed. I checked Miles again. He remained unconscious but continued to breathe steadily. I then helped the others organise the supplies and separate what they would need while they waited at camp. No one complained about carrying or rearranging extra kit once the seriousness of the situation had sunk in.

"What about Miles's things?" Oliver asked, indicating the tent.

"I'll deal with them," I said. "I need the rest of you to inspect the open ground I described. Don't cut or remove anything. Just identify loose equipment, bags or branches that could be blown about, then return here. The rescue team will decide whether the aircraft can land or must winch."

After giving them precise instructions and an agreed regrouping procedure, I turned back to Miles. I packed his belongings, leaving out only what he might need during the evacuation.

While the others were away, I removed the stone from my jacket pocket, wrapped it in a spare shirt and buried it deep inside my own rucksack. The decision felt wrong, yet the thought of leaving it behind or surrendering it produced a strange, immediate resistance in me, almost like a thought that was not entirely my own.

When I checked Miles again, his eyelids fluttered. I bent closer, hoping he was waking, but his eyes stayed shut and he did not react to my voice or touch. The blood around his ears had dried completely. I worried about injuries I could not see.

The others returned, and we settled down to wait. Morning passed with agonising slowness. I checked Miles's vital signs regularly, distributed food and hot drinks, and tried to keep everyone calm. No one mentioned the stone. I offered no information about it.

"How long until the helicopter arrives?" Graham asked for the third time, consulting his expensive watch.

"They said it could take up to six hours," I replied, keeping the irritation from my voice. "These responses take time."

"And they're definitely coming?" Alistair asked. "I can make calls if we need to hurry matters along."

"They're coming. The best thing we can do is remain ready and follow the instructions from Police Scotland and mountain rescue."

I returned to Miles and checked his pulse again. It was still steady. His breathing had not changed, but he showed no sign of waking, and my concern deepened with every passing hour.

Whatever the stone had done seemed to reach beyond physical injury. It had touched his mind through the music. The object lay dormant in my rucksack, but I could not rid myself of the feeling that it was merely waiting and gathering strength.

I touched the place where it had first rested in my pocket, half expecting to feel warmth or vibration through memory alone. There was nothing, only the recollection of that impossible music and the image of Miles in the moonlit clearing with blood streaming from his ears.

As the wait dragged on, the clients grew restless.

"Any change?" Oliver asked, his expensive walking boots crunching on the thin snow as he approached Miles's tent.

"No. Pulse steady, breathing regular, still unconscious."

Alistair joined us with his satellite phone in one hand. "Bleeding from both ears isn't consistent with simple exhaustion."

"I never said it was," I replied. "It could be a neurological event, an injury we haven't found or a problem within the ears themselves. We won't know until clinicians assess him."

Rupert stood slightly apart from the others. "You were with him last night, weren't you? I thought I heard voices."

The other three turned to me. I felt the weight of the stone inside my rucksack, a physical reminder of everything I could not tell them.

"I found him walking in an altered state," I said. "When I tried to bring him back, he collapsed. That was when I saw the bleeding."

"Sleepwalking?" Graham scoffed. "Miles has never sleepwalked in his life. We've been away on golfing weekends together for years."

"People don't usually sleepwalk in strange woodland after days of exertion," I said. "Exhaustion, cold, unfamiliar surroundings and disrupted sleep can produce unusual behaviour."

Alistair stepped closer and lowered his voice. "Callum, we're paying clients. If there's something you aren't telling us about what happened to Miles-"

"There is nothing else I can usefully tell you," I cut in. "I found him, brought him back and requested medical evacuation. That's the situation."

The lie settled heavily in my chest. In 20 years as a guide, I had never concealed a safety issue from clients. But how could I describe what I had witnessed? The vibrating stone, the impossible music, Miles standing entranced while his ears bled? They would think me delusional, or suspect that I had caused his injuries.

For the next two hours I maintained my vigil, checking Miles's vital signs, sipping water to remain alert and answering repeated questions from the increasingly anxious group. Each time I entered the tent, I half expected to find the stone back in his hands. He remained still, pale against the dark sleeping bag.

Then Oliver shouted and pointed towards the ridge.

"There!"

A dark shape had appeared against the pale sky. The thudding of rotor blades reached us a moment later and grew steadily louder.

"That's the helicopter," I said. "Get ready, but keep loose kit secured. Follow the rescue crew's signals and stay clear until they approach you."

The Coastguard aircraft swept over the ridge and circled the site while the crew assessed the terrain. Downdraught lashed the branches and sent loose snow streaming across the clearing. They judged the ground unsuitable for a full landing and moved into a hover over the more open area.

A Coastguard winch paramedic descended with rescue equipment while, from the direction of the track, two members of the volunteer mountain rescue team arrived at camp. One was a qualified mountain leader sent to remain with the four clients and escort them out once conditions allowed; the other came with the stretcher party to assist with Miles.

Together we wrapped Miles in an emergency bivvy and transferred him on to a mountain rescue stretcher. His eyelids fluttered as we secured him, the first response I had seen since he collapsed.

"Miles, can you hear me?" I asked, but his eyes remained closed.

We carried him the short distance to the winching area. I gave the paramedic a rapid handover over the roar of the helicopter.

"Male, mid-forties. Unconscious since shortly before dawn. Bleeding from both ears, no visible head injury. Pulse and breathing stable throughout. Brief eyelid movement, but no meaningful response."

The paramedic checked his pupils, airway and vital signs before securing him for the winch.

"Are you travelling with him?" he asked.

I looked back at the other four clients. They stood beside the five tents still at camp, with the replacement guide and mountain rescue member taking charge of their supplies and communications.

"We'll stay here until they escort us out," Oliver said, reading my hesitation.

I nodded to the paramedic. "Yes. Miles is my responsibility."

The casualty was winched aboard first. I followed with my rucksack strapped tightly to me, feeling the hard outline of the wrapped stone beneath the spare clothing.

As the helicopter climbed away, I looked down at the camp. The four clients stood with the two rescuers among the tents, shrinking until trees and folds in the ground hid them from view.

Inside the aircraft, the crew worked efficiently, attaching monitors to Miles and establishing intravenous access. I pressed myself against the cabin wall, keeping clear while watching his face.

About 20 minutes into the flight, his eyelids fluttered again and then opened fully.

"He's waking," I told the winch paramedic.

The paramedic bent over him at once. Miles's eyes darted around the cabin, confusion and fear plain on his face. His mouth opened and closed without producing a sound. Then he raised both hands to his ears and pressed his palms against them in obvious distress.

"Miles," I said, leaning closer. "You're safe. We're taking you to hospital."

He did not respond. He continued touching his ears, panic twisting his expression. When I put a hand on his arm, he finally looked at me.

"Can you hear me?" I asked slowly, making the words clear on my lips.

Miles shook his head violently, then winced. He pointed at his ears, his fingers trembling.

"He doesn't seem able to hear," I told the paramedic. "Could the bleeding mean a ruptured tympanic membrane?"

"It's possible," the paramedic replied, examining his ears with a light. "It may be temporary or more serious. ENT will need to assess him at Raigmore."

For the rest of the flight, Miles drifted between wakefulness and sleep. Each time he woke, the same frightened realisation returned. We could only suspect acute hearing loss; no one could yet say how severe or lasting it might be.

I kept my hand on his arm, offering what comfort I could. The stone remained cold and silent inside my rucksack, a hidden reminder of what had happened.

Depending on the wind and cloud around the mountains, the flight to Inverness took a little under 40 minutes. The helicopter set down at the designated receiving site, where an ambulance crew transferred Miles to Raigmore Hospital's emergency department.

I followed with my rucksack clutched close.

Inside the hospital, staff directed me to a waiting area while Miles underwent urgent assessment. An NHS liaison officer approached with a form in hand.

"Are you the mountain leader? Callum Fraser?"

I nodded, suddenly conscious of how I must look: unwashed, exhausted and still dressed for the hill.

"I need to confirm the patient's identity and the circumstances of the incident," she said. "The clinical team is concerned about substantial hearing loss and is trying to establish a cause."

I weighed every word before answering.

"We were on a guided trek in a remote part of the Cairngorms. I found Miles unconscious before dawn with blood coming from both ears. He had been behaving strangely the previous day - distracted, withdrawn and eating very little."

"Were there any loud noises nearby? Explosions, firearms, machinery or equipment failure?"

"No," I said, and the lie came more easily now. "Nothing like that. It had been an ordinary trek until I found him."

She recorded my answer.

"Had he complained of ear pain, dizziness or difficulty hearing before the incident?"

"No. Nothing."

She confirmed Miles's full name, date of birth and emergency contact, then asked for the expedition details and the contact information for the outdoor firm in Aviemore. There was no discussion of payment or insurance as a condition of treatment. After taking the information, she left me alone.

I sat in the waiting area for three hours and declined several offers of tea and coffee. I needed to remain alert and decide what to do next. My thoughts kept returning to the stone inside my rucksack.

At last, a doctor in scrubs approached.

"Mr Fraser? I'm Dr Priya Shah. I've been treating Mr Redmond."

I rose, acutely aware of the weight on my shoulder. "How is he?"

"Physically stable, but I'm afraid the initial findings are serious."

Dr Shah indicated that I should sit and took the chair opposite.

"Mr Redmond has suffered severe bilateral sensorineural hearing loss. In simple terms, the sound-detecting hair cells within both inner ears have been damaged."

"Will it improve with time or treatment?"

She shook her head. "We need further tests before making a final prognosis, but the loss appears profound and is likely to be permanent. The injury pattern is highly unusual. Damage of this severity is generally associated with extreme sound exposure - an explosion, an industrial accident or prolonged acoustic trauma. You are certain there was no loud noise?"

"None," I said, feeling sick.

The music had done this. Miles had heard its full force while I had perceived only a weakened resonance, as though the stone had directed itself towards him and allowed the rest of us merely an echo.

"That is what makes this so difficult to explain," Dr Shah continued. "The affected frequencies form an anomalously precise pattern. It is almost controlled in its distribution. I have never encountered an injury quite like it."

I swallowed. "What happens now?"

"We're admitting him for observation and urgent ENT and audiology assessment. Once the extent and permanence of the loss are confirmed, the team will discuss rehabilitation, hearing aids and whether he might eventually be assessed for cochlear-implant candidacy. I've also requested psychiatric support. He appears to be suffering acute psychological trauma in addition to the physical injury."

"What sort of symptoms?" I asked, although I could guess.

"Extreme agitation and apparent hallucinations. He repeatedly gestures as though he is holding something and listening to it. When we communicate in writing, he asks about music and a stone. Does that mean anything to you?"

I shook my head. The denial burned in my throat.

"No. Nothing."

Dr Shah studied me for a long moment, as though she sensed the omission.

"Police Scotland may need a further statement because the injury occurred during a guided expedition. Your employer and its insurer will also contact you in due course."

My stomach tightened. "Of course. I'll cooperate fully."

"You may see him if you wish, but I should warn you that he is very distressed. We've given him a mild sedative to help settle him."

"I'd like to see him."

I stood with the rucksack still over one shoulder. Dr Shah led me through the emergency department to a curtained bay where Miles lay on a hospital trolley. His outdoor clothes had been replaced by a hospital gown, and his face looked drawn beneath the harsh fluorescent lights.

When he saw me, his eyes widened and he tried to sit up.

"Easy," I said, forgetting for a moment that he could not hear me.

Miles snatched a notepad from the bedside table and wrote frantically. He thrust the page towards me.

"Where is it?"

I pretended not to understand. He wrote again, pressing so hard that the pen tore the paper.

"The stone. Give it back."

"Miles, you need to rest," I said aloud, deliberately relying on words I knew he could not hear.

I took the notepad and wrote, "You had an accident. You need to recover."

He tore it back from me and scrawled, "I need the stone. It was talking to me. Give it back."

I took the pad once more and wrote, "There is no stone. You were hallucinating."

Miles's face contorted with rage. He hurled the notepad across the room and lunged for my rucksack. I stepped back, keeping it beyond his reach. A nurse hurried in, alerted by the commotion.

"He needs to rest," she said firmly, giving me a pointed look.

I nodded and backed towards the curtain.

"I understand. I'll come back later."

Miles's eyes followed me. They held a desperate, knowing look that chilled me more than any Highland storm ever had. He knew I had the stone, and he wanted it back.

In the corridor at Raigmore Hospital, I leant against the wall, my heart pounding. The stone lay in my rucksack, seemingly harmless now, but I knew better. It had destroyed Miles's hearing and perhaps damaged his mind. Yet I could not bring myself to get rid of it.

Something about it demanded to be studied and understood, but safely, far from vulnerable minds like Miles's. That thought felt reasonable at the time. It may not have been entirely my own.

Two hours later, after speaking to NHS liaison staff and giving Police Scotland a carefully edited account of what had happened, I sat in the hospital cafe, picking at a sandwich while I considered my next move. Dr Priya Shah had confirmed permanent bilateral sensorineural hearing loss, with an anomalous frequency-specific pattern she could not readily explain. Miles would need urgent ENT and audiology follow-up. Once the full extent of the damage was established, there would be discussions about hearing aids or possible cochlear-implant candidacy, as well as psychological support.

I had deliberately omitted the most important part of the truth. The weight of that settled on me like a physical burden, almost as heavy as the stone in my rucksack. In twenty years as a mountain leader, I had never encountered anything like it - something that defied explanation and caused terrible harm without leaving evidence anyone would believe.

I made my decision.

I would keep the stone secure and away from other people. I would research the place where Miles had found it. And I would carry the truth alone, because who would believe me if I shared it?

As I left the hospital that evening, I glanced back at the building where Miles lay, permanently changed by what he had heard.

Music that was not meant for human ears. Messages from something ancient beneath the mountains, something that had used him and discarded him when he could no longer serve as its listener.

I adjusted my rucksack, feeling the weight of the stone inside, and walked towards the car park, where a company minibus waited to take me back to the firm's base in Aviemore. The stone remained silent and dormant, but I knew what it could do. That knowledge would haunt me long after the evening ended.

When I returned to my cottage outside Grantown-on-Spey, I kept the stone. I carried it down to the stone-floored cellar and locked it inside an old steel deed box that an elderly client had given me years before. It was meant for property papers and valuables. Somehow it seemed appropriate, although I doubted steel would contain whatever the stone truly was.

I placed it inside, still wrapped in the shirt I had used in my rucksack, and closed the lid with a solid click.

For the first week, I checked it every day. Each time, I unlocked the box, carefully unfolded the cloth and examined the stone. It remained completely inert, showing no sign of the vibrations or impossible properties it had displayed in the glen. It was merely a smooth, perfectly round object about the size of a cricket ball, shifting between deep grey and black according to the angle of the light.

I would hold it briefly, waiting for the tingling sensation to return, but my palms felt normal. No music came. There were no vibrations. Nothing.

By the second week, I checked it less often. The stone stayed silent, cold and lifeless, as if it had never done anything unusual at all.

The company gave me two weeks of paid leave after the incident, standard procedure after a serious client emergency. I spent most of it at home, avoiding calls from Oliver, Rupert, Dr Alistair Khan and Graham. Their messages accumulated. They asked about Miles, about what had really happened and, improbably, whether they could book me again the following year.

I let every call go to voicemail.

When I returned to work, my supervisor handed me a stack of incident forms. I recorded the same facts I had given Police Scotland, the clinicians and the company.

Miles Redmond had been behaving strangely. Near dawn, I found him unconscious in the snow with blood coming from his ears. I activated my satellite messenger, contacted Police Scotland through 999 and requested mountain rescue. The four remaining clients stayed at camp with food, shelter and communications until a replacement qualified guide and a member of the volunteer mountain rescue team reached them.

Nothing about the stone. Nothing about the music. Nothing about the crucial details I had withheld from everyone involved.

The outdoor firm's insurer contacted me later and accepted the same account. Mountain leaders and rescue teams encountered inexplicable medical crises from time to time. Acute stress, cold, exhaustion and an undiagnosed neurological event left enough room for uncertainty.

During quiet evenings at home, I researched the history of that part of the Cairngorms, but found no clear record of similar phenomena or mysterious stones. I examined geological surveys, archaeological reports, estate records and collections of local folklore. The wider region was known for its glacial geology, ancient settlements, erratic weather and scattered finds from different periods. Nothing in the reputable material described a stone that sang impossible music or drove a man towards madness.

There were fragments in two old estate papers, both written long after the events they claimed to record. One mentioned a "humming place" below a nameless bealach. Another contained a second-hand tale about builders beneath the hills, loosely labelled Pictish by a Victorian antiquarian who supplied no evidence. Neither document attributed the story to any living Gaelic tradition, and neither gave a location precise enough to prove a connection.

Still, I copied both references and hid them with my private notes.

The company assigned me to routes elsewhere in the Highlands. I did not object. In fact, I requested the change, telling my supervisor that I wanted different scenery. He seemed relieved, probably concerned that I might be reluctant to guide at all after what had happened.

The truth was that I had no problem guiding. I simply could not return to that glen, that sensitive conservation site or the remote tract surrounding it.

Months passed. Autumn turned to winter, and winter to spring. I led groups through snow-covered glens and across icy ridges in Glen Affric, Lochaber and Perthshire. I taught winter mountain skills to corporate teams and guided photographers to places where they might see ptarmigan or mountain hare.

I did my job well, as I always had, but something in me had changed. I listened more closely to the sounds of the hills - wind moving through Scots pine, the cries of birds, burns rushing over stone.

They were ordinary sounds, following patterns I had known for twenty years. Nothing resembled what I had heard on that expedition. Nothing resembled the music that had destroyed Miles's hearing.

Months later, the experience still haunted me. After hundreds of successful days in the Scottish hills, I knew I would never return to that particular part of the Cairngorms. I had made peace with the decision. There were plenty of other beautiful places where I could take clients, places without singing stones.

Yet the memory of those unearthly harmonies, and of Miles kneeling entranced in the snow, continued to disturb my sleep.

I would wake in the middle of the night certain that I could hear faint traces of the music. I would lie still and listen until I persuaded myself it was only the central-heating pipes or a neighbour's heat pump. Normal household noises. Nothing supernatural.

One morning in early summer, a solicitor's letter arrived by Royal Mail Signed For.

I opened it at the kitchen table while my tea went cold beside me. Miles's solicitors requested every document connected with the expedition: my guide logs, Ordnance Survey route plans, weather reports, equipment checklists, medical incident forms, client waivers and any photographs or recordings in my possession.

The letter did not explicitly state that proceedings had begun, but its meaning was plain. Miles was preparing a possible negligence claim, perhaps against the company, perhaps against me personally. It referred to the serious and permanent injuries sustained while he was under my professional care and demanded disclosure of all material factors that might have contributed to the incident.

I supplied only the official records, preserving the same omissions I had made from the beginning.

I copied everything held at the firm's Aviemore base: route plans, forecasts, equipment lists, emergency logs and incident forms. It was all factual and verifiable. It was also incomplete.

Nothing about the stone. Nothing about the music.

I considered writing to Miles directly. I wanted to ask how he was coping and explain what I knew, or what I believed I knew. But what could I say? That an ancient stone had sung to him and destroyed his hearing? That something beyond human understanding had chosen him as its listener?

He might think I was mocking him or inventing an absurd story to conceal professional negligence.

Or worse, he might believe me.

He would know I still had the stone. He would want it back.

So I sent the documents to his solicitors and said nothing more.

Let them build their claim around exposure, an undiagnosed medical condition or failures in expedition management. Let them accuse me of negligence or challenge the company's procedures. Let them seek disclosure and present evidence that made sense in a Scottish court.

I had survived an encounter with something beyond human understanding, and I carried that knowledge alone. The official account remained consistent for Police Scotland, Raigmore Hospital, the outdoor company, its insurer and Miles's solicitors. I had not invented a single fact.

I had only omitted the truth.

Beneath my cottage, locked inside an old steel deed box in the stone-floored cellar, the singing stone remained silent. I told myself I had kept it to protect others, yet sometimes, lying awake and listening to the pipes, I wondered whether I had chosen to keep it at all.