The Playback Signal

I worked out of Ofcom's Birmingham office, in spectrum enforcement. Most of what we handled was paperwork: signal breaches, unlicensed community transmitters, illegal FM stations, poorly installed radio equipment. Nothing that kept me awake at night. I was already awake at night anyway.

Sleep did not come easily to me. It had not for a long time. I would lie in my flat with the blinds shut and a desk fan running through winter because I needed the steady background noise, while my brain cycled through everything I had not finished. Forms I needed to file, calls I should have returned, equipment checks I had skipped because I was running late.

It all stacked up in there, looping. Lucy Bennett, my counsellor, told me to make lists. Physical lists.

"Write it down," she said, "and your brain can let go of it."

So I did. I kept a dark blue hard-backed pocket notebook with squared paper. It probably made me look pretentious, but never mind. Every morning I wrote out what needed doing, numbered and specific, then crossed things off as I went.

It helped. Sort of.

The job itself was fine. I liked the technical side.

Signal analysis, spectrum monitoring, interference tracking. A lot of the other officers hated that work. Too much maths, too much time staring at graphs and readouts. They wanted field enforcement, the face-to-face part where you knocked on a door and handed someone an enforcement notice.

That was not really my thing. I took the calls they did not want, the ones that required sitting in a van for six hours with a spectrum analyser, triangulating an intermittent bleed into a rural broadcast service. The ones where you had to read thirty pages of technical logs to find the two sentences that mattered. I did not mind. It was methodical. Predictable, most of the time.

The report about Jodrell Bank came in on a Wednesday. I was at my desk, halfway through a mobile mast compliance report concerning a site near Telford, when my supervisor forwarded the email.

The subject line read: Urgent protected-site interference report - staff welfare incident.

That got my attention.

The protected radio environment around Jodrell Bank Radio Observatory was serious. Restrictions and coordination measures were used to prevent harmful radio interference, supported by UK spectrum regulation and local planning controls. It was tightly managed, and for good reason. Radio astronomy depended on detecting emissions so faint that careless equipment kilometres away could bury them.

It was not the kind of place where a major interference event could be shrugged off. I opened the email.

The observatory had detected a powerful unidentified signal affecting its observations. That alone would have warranted a response.

But the rest of it was what made it more than paperwork.

Two technicians had abandoned their shift. They had simply walked out during an observation, without explanation or communication. Security found them later, sitting in a car in the east car park, unresponsive. Not unconscious. Just staring.

When they finally came round, neither could explain what had happened. They did not remember leaving their posts. Several observation sessions had been completely ruined. Data had been corrupted, recordings wiped and equipment left running in configurations that made no sense.

The report did not use the word fugue, but that was what I thought when I read it. It was the word that lodged in my head.

I should have handed it off. This was bigger than ordinary interference, bigger than my usual scope, but I did not.

I rang the number at the bottom of the email and said I would take it. Maybe I was curious. Maybe I wanted something that was not another mobile mast report. I do not know.

I told myself that somebody had to go, and I was already reading the file, so it might as well be me.

They told me to drive to Macclesfield and meet the team there.

Team. That should have been a clue.

The drive north from Birmingham took roughly two hours, allowing for traffic. I left shortly after lunch and followed the M6 before cutting onto Cheshire A-roads. The landscape changed from urban outskirts to low wooded ridges and farmland divided by hedges. I did not mind driving. It gave me time to think, and time to go over the details again.

I kept returning to the technicians and the way the report described them: blank, unresponsive, with no memory of the event. That was not normal interference. It was not unlawful or badly configured private mobile radio equipment bleeding into the wrong frequency. It was something else.

I reached Macclesfield at about 16:30 and found the meeting point, a Premier Inn near the Silk Road. Three vehicles were parked together outside: two official fleet vehicles and one contractor's van.

Helen Mercer was waiting in the lobby. I knew Helen.

She was my manager's manager, the regional lead for field operations. Seeing her there in person was unusual. Helen did not conduct field inspections. She held conference calls, attended budget meetings and signed off compliance audits.

She looked exactly as she did on video calls. Blonde hair pulled tightly back, blazer over a polo shirt, identification lanyard and clipboard in hand. She had the permanent expression of someone who was already annoyed before you opened your mouth.

"Navarro," she said.

It was not a question.

"Yes. Hello."

She did not smile. She nodded and gestured towards the corridor.

"We're in the conference room. I'll brief everyone together."

Everyone. That word again.

I followed her along a corridor that smelt of stale coffee and lemon cleaner. The conference room was small, barely larger than a cupboard, with a folding table and six chairs. Three people were already inside.

Helen did not waste time.

"This is Daniel Navarro, Ofcom spectrum enforcement. He'll be handling the technical assessment."

I gave a small wave. I did not know what else to do.

"Callum Price," Helen continued, indicating a man in work boots and a tool belt. "Electrical contractor."

Callum nodded to me. He was younger than I was, perhaps in his late twenties, and solidly built. He had the hands of somebody accustomed to actual work: scarred knuckles and a burn mark along one forearm. He did not look nervous. He looked ready.

"Dr Aisha Rahman," Helen said. "UK Health Security Agency. She's attending as a clinical behavioural specialist because of the unexplained symptoms among the staff."

Aisha was small and slim, with dark hair pulled back into a ponytail. She wore rectangular glasses and had a notebook open in front of her, pen already in hand. She looked up and gave me a polite smile. Professional. Clinical.

UKHSA.

That sat heavily with me.

"And Sergeant Tom Hargreaves, Cheshire Constabulary. He'll be our police escort."

Tom was a large man, about 1.90 metres tall, in uniform and protective vest, with a radio clipped near his shoulder and a body-worn video camera mounted on his chest. He had the kind of presence that made you sit straighter without meaning to. He nodded to me, and I nodded back.

Helen placed her clipboard on the table.

"We're treating this as a standard interference inspection with health and safety oversight. The observatory has reported harmful interference within its protected radio environment. Our job is to locate the source, document any breach, disable the source if we can do so safely, and determine whether formal enforcement action is required."

She slid a stack of papers across the table. Pre-prepared statutory access notices, interference notices and site-entry paperwork, all completed except for the signature lines.

That bothered me.

A standard inspection did not usually involve a UKHSA behavioural specialist. It did not require a uniformed Cheshire Police sergeant as an escort. It certainly did not come with every possible form prepared before we had even seen the site.

I said nothing. I merely added it to the list in my head.

Helen continued.

"We'll travel to the observatory in two vehicles. Sergeant Hargreaves will lead in the marked response car. The rest of us will follow in the Ofcom van. Navarro, Price and Dr Rahman will come with me.

"Once on site, we'll conduct the inspection, locate and disable the source if possible, then return here for debrief."

She said it as though we were checking a shop sign for a faulty electrical transformer.

Callum spoke up.

"What's the signal profile?"

Helen glanced at her clipboard.

"Intermittent. High power. No identifiable modulation pattern. The observatory hasn't managed to isolate it."

"So we don't know what we're looking for," Callum said.

"We'll know when we find it," Helen replied.

Flat. Certain.

Aisha made a note. I watched her handwriting: small, neat and controlled.

"What about the technicians?" I asked. "The two who walked away from their posts."

Helen looked at me.

"They've been released after medical assessment. No underlying conditions were identified, but they don't remember what happened."

"Neither of them?"

"Correct."

I waited for her to add something. She did not.

"Is that normal?" I asked.

"That's why Dr Rahman is here," Helen said.

She did not elaborate. Aisha glanced up from her notebook but said nothing.

Tom shifted in his chair.

"Are we expecting trouble?"

"No," Helen said. "But protocol requires police presence after the staff welfare incident. You're there to facilitate access and secure the site if necessary."

Tom nodded. He did not look concerned. He was simply doing his job.

I looked around the table. A field manager who should have been behind a desk, a competent electrical contractor, a UKHSA clinical behavioural specialist, a police sergeant and me.

It was the kind of team you assembled when you did not know what you were dealing with but wanted every possibility covered.

Or when you knew exactly what you were dealing with and did not want to say it aloud.

Helen closed her clipboard.

"We leave in ten minutes. Check your equipment, use the toilet, do whatever you need to do. We won't be stopping once we're on the road."

Everyone stood. Callum went out to his van. Aisha remained at the table, still writing. Tom stepped into the corridor to make a call.

I opened my dark blue notebook and added several lines.

Pre-prepared notices.

UKHSA on site.

Technicians, no memory.

Helen attending in person.

I did not know what it added up to yet, but it felt like pieces of something.

Helen was watching me.

"Problem, Navarro?"

"No. Just making sure I'm clear on everything."

"Good. Stay close once we're there. Don't wander off."

I nodded.

Ten minutes later, we were in the vehicles. Helen drove a white Vauxhall Vivaro carrying discreet Ofcom markings, with racks of equipment secured in the back. I sat in the passenger seat. Callum and Aisha were behind us.

Tom's marked police response car pulled out first, its blue lights off, and we followed.

The roads narrowed as we left Macclesfield behind. Low ridges and farmland rose around us, and trees pressed close on either side in places, dense and dark although daylight remained.

The signal on my mobile phone dropped to nothing.

Nobody said much. Helen kept her eyes on the road. Callum checked something on his tablet. Aisha stared through the window, her notebook resting on her lap.

I went over the list again in my head.

The signal. The technicians. The composition of the team. The paperwork prepared in advance.

It did not fit together cleanly. That bothered me.

Lucy's voice came back to me.

When things do not make sense, write down what you know. Not what you think. Only what is true.

What I knew: we were going to a radio observatory to investigate interference. Two people had experienced some kind of fugue state. Five people from Ofcom, UKHSA, Cheshire Constabulary and a specialist contractor had been sent to deal with it.

What I did not know: why.

The van struck a pothole and jolted. Helen did not slow down.

Ahead of us, Tom's police car turned onto a smaller road. There were no public direction signs, only gravel and trees.

I could feel it starting. The tightness in my chest. The buzz in my head that meant my thoughts were spinning up.

I pressed my thumb against my index finger and counted backwards from ten.

It helped. A little.

We kept driving. The gravel ended at a security gate that stood unlocked. Tom got out, pushed it open and drove through. Helen followed in the van.

Beyond the gate, the road returned to tarmac and the trees drew back enough to reveal a secured technical compound. The great white radio telescope dish stood to the left, tilted towards nothing in particular. Nearby was a smaller metal antenna shed, aerials rising from its roof. Straight ahead stood a low brick control building with narrow windows, a flat roof and several vents.

The sun had not set, but it was low enough to give the clearing that washed-out, pre-dusk colour in which everything looked faintly grey.

Tom parked near the front of the control building. Helen pulled the van alongside him.

I got out first. My legs were stiff from the drive, and I rolled my shoulders once, trying to loosen the tightness. The air smelt normal. Damp earth, grass and trees. Nothing chemical.

But the building's front doors had been propped open with a yellow plastic cone wedged beneath each one.

That was wrong.

I had conducted perhaps a dozen site inspections over the years: broadcasting facilities, mobile masts, university laboratories, government offices and equipment centres. Places housing sensitive equipment did not leave doors propped open. They controlled access. They maintained environmental conditions. They locked down.

They did not allow insects, weather and random humidity to drift through whenever they pleased.

Helen came round the front of the van with her clipboard. Callum climbed out from the back and adjusted his tool belt. Aisha stepped down last, already holding her phone.

"The front entrance is compromised," I said. It probably sounded more formal than I intended. "The doors have been propped open."

Helen glanced at them.

"Noted."

Tom walked over, his thumbs hooked into his vest.

"Could be a ventilation problem. Cooling fails, people open doors."

"Maybe."

It still bothered me.

We approached the entrance together. Tom went first, Helen directly behind him, with Callum, Aisha and me following.

The building had the institutional look common to technical facilities: dark brick, narrow windows with blinds lowered halfway, metal trim around the door frames. A sign beside the entrance read Jodrell Bank Radio Observatory. Authorised personnel only.

This was not a real documented incident, I reminded myself. It was an unexplained report involving people whose names I had not been given. Yet standing there, looking at the familiar institution's name, I felt the warning in my chest tighten.

Tom stepped inside first. I followed.

The beeping began immediately.

It was not loud. Only steady.

A security keypad was fixed to the wall on the right, roughly two metres inside the entrance. It was a small grey box with a numerical pad and a red LED blinking in time with the sound.

Beep.

Beep.

Beep.

The same interval every time. Perhaps one beat per second. Perfectly even.

"Someone's left it unlocked," Tom said, looking at the panel.

"Or bypassed it," Callum muttered behind me.

I stared at the keypad. The beeping did not sound like an alarm. Alarms escalated. They became louder or faster, or cycled through tones.

This was a heartbeat. Mechanical and constant.

Helen moved past us into the corridor.

"Stay together. We document as we go."

The corridor ran straight ahead, with doors on both sides and fluorescent panels overhead. Most of the lights were working, but two fittings were dead, leaving dark gaps at intervals of about three metres.

The air felt thick. Not hot exactly, but stale. I breathed through my nose and tasted recycled air that had remained too long in one place.

Aisha walked beside me, notebook open and pen moving.

"The ventilation might be cycling incorrectly," she said quietly.

"Yes."

I kept my eyes ahead. The keypad remained audible behind us, muffled now but still steady.

We passed the first door on the left. A plaque identified it as STORAGE. It was closed, with an unlocked handle.

The next door on the right stood open by a few centimetres. Through the gap I could see part of a desk, a dark monitor and a coat draped over a chair.

Then I saw the clocks.

Four radio-room clocks hung above a noticeboard cluttered with safety notices and a faded electrical-safety poster. They had white faces, black hands and black numerals. Labels beneath them read UTC, LOCAL, RECEIVER and ARRAY.

All four showed incompatible times.

UTC read 16:53.

LOCAL read 18:12.

RECEIVER read 14:37.

ARRAY read 03:08.

I stopped.

Aisha noticed.

"What is it?"

I pointed. She looked up, then wrote something in her notebook without speaking.

Helen continued ahead, her shoes clicking against the lino. Tom stayed close to her. Callum glanced at the clocks, frowned and walked on.

I took out my phone to check the actual time. There was still no service, but the clock worked.

17:41.

None of the wall clocks was close.

"Daniel," Helen called from farther along. "Keep up."

I put my phone away and walked faster.

The corridor turned left. When we followed it, the sound changed.

The keypad was no longer the dominant noise. There was something else: a low, rhythmic mechanical hum, and beneath it a sharper, repetitive clicking.

We rounded the corner and saw him.

A man stood in front of a large office photocopier, feeding blank sheets into the document feeder one at a time. He wore a wrinkled button-up shirt with its sleeves rolled to the elbows and an observatory identification card clipped to a lanyard. His thinning grey hair was combed straight back. He had a narrow face and ink smudges on his fingers.

The photocopier was running. Its output tray overflowed with printed sheets, and more had spilled across the floor in a disordered pile.

I stepped closer.

The pages were not blank. They were packed with numbers in tight rows, edge to edge, without margins. At first glance I could see no pattern. Only digits.

The man did not look at us. He took another blank sheet from a stack on the counter, placed it carefully in the feeder and pressed the button.

The photocopier hummed. A fresh page slid into the output tray.

Helen stepped forwards, her clipboard held against her chest.

"Excuse me."

The man did not respond. He reached for another blank sheet.

"Sir," Helen said, louder.

She raised her identification.

"I'm Helen Mercer from Ofcom. We're conducting a formal inspection under Ofcom's statutory spectrum-enforcement powers. I need to speak to your site supervisor."

The man placed the sheet in the feeder and pressed the button.

Helen's mouth tightened. She glanced at Tom and then back at the man.

"Can you hear me?"

The man opened his mouth.

"6149027731," he said.

His voice was flat and without inflection. He did not look at Helen or at any of us. He kept his eyes on the photocopier and continued feeding it paper.

"480316592."

My jaw tightened. The cadence was too even, too smooth. There was no perceptible breath between the groups, only a steady stream.

"76104."

Aisha stepped forwards, pen poised over her notebook. She tilted her head and leant slightly closer, watching his face.

"2259830."

The rhythm locked in.

I do not know how else to describe it. It was neither loud nor aggressive, but it had weight. Physical weight. It pressed into the space between my ears and sat there.

"4176."

Aisha leant nearer. Her pen moved in small marks across the page.

I seized her arm and pulled her back. She stumbled, caught herself against the wall and stared at me.

"What are you-"

"Don't," I said.

My voice was sharper than I meant it to be.

"Don't listen that closely."

Helen turned towards me, eyebrows raised.

"Navarro."

I did not release Aisha's arm.

The man continued reciting with the same rhythm and flatness.

"6149027731. 480316592. 76104. 2259830. 4176."

I felt it in my jaw, not my ears. A low, crawling pressure, as if the sound were bypassing everything normal and passing directly into the bone.

My teeth wanted to move. My mouth wanted to form the numbers.

I let go of Aisha and stepped back.

"6149027731."

He had looped. The same sequence was beginning again.

Callum moved to one side and studied the photocopier's output tray. He bent, picked up one of the printed sheets and held it towards the light.

"They're all the same," he said. "The same groups, over and over."

"480316592."

Tom rested a hand on his radio but did not transmit. He looked at Helen.

"Should I restrain him?"

"On what grounds?" Helen asked, though some of the edge had left her voice.

She was staring at the man now, her clipboard held slightly lower.

"76104."

I pressed my thumb against my index finger and counted backwards from ten in my head. The buzzing did not stop. It remained in my jaw and hummed.

Aisha was writing again, but she kept her distance this time. Her hand moved quickly in shorthand I could not read.

The photocopier kept running. The man kept feeding it blank sheets. The output tray kept producing pages covered in numbers.

Helen cleared her throat. She straightened, removed a prepared form from her clipboard and held it towards him, although he was not looking.

"Sir, this is a statutory notice of inspection. You are required to provide access to relevant equipment and personnel on this site. If you cannot comply, we will proceed in accordance with our enforcement powers."

"2259830."

She lowered the notice and looked at Tom, then at me.

I shook my head. I did not have an answer.

"4176. 6149027731."

The air felt heavier. The ventilation still hummed, but the cadence threaded beneath it, low, invasive and wrong in a way I could not name.

This was not ordinary interference. It was not a spectrum breach. It was nothing described by the paperwork Helen had distributed in the hotel conference room.

The building had been wrong from the start: the propped doors, the clocks, the stale air. Now there was a man reciting numbers without pausing for breath or making eye contact while a photocopier produced pages nobody would ever read.

We had walked into something procedure would not fix.

Callum moved first.

That was what I remembered most clearly about that moment. While the rest of us stood listening to the man repeat the same loop, Callum turned away from the photocopier and began examining the corridor.

"Something must be generating this," he said, mostly to himself, I think.

He went farther along, checking the doorways.

I followed. I probably should have asked Helen first, but I was relieved to have something to do besides stand there feeling my jaw try to reproduce the rhythm.

The first door on the right opened into a small office containing a desk, two filing cabinets and a faded electrical-safety poster. Nothing obvious.

Callum moved on.

The second door was locked. He tested the handle once and continued.

The third opened into a compact equipment room. Metal racks, about a metre and a half high, stood along two walls. They held radio receivers, spectrum analysers, signal generators and test equipment. It was a standard monitoring arrangement for a facility of that kind.

Most of it was dark, but one receiver in the middle rack had a green power LED illuminated.

Callum saw it at the same time I did. He stepped closer and leant in to inspect the rear panel.

"Aerial ports are terminated," he said.

I looked. He was right. A 50-ohm terminator was fitted to the BNC connector. There was no aerial and no input.

"So it isn't receiving anything," I said.

"It shouldn't be."

Callum tapped the front panel with one knuckle. The LED remained green.

"But it's powered."

For a moment I thought we had found it: a misconfigured test unit left running, perhaps looping a stored signal or replaying corrupt data. That happened. Equipment was put into the wrong mode, began outputting rubbish and went unnoticed until it caused interference.

A simple fix. Isolate it, document the breach and prepare the appropriate notice.

"Shut it down," I said.

Callum reached behind the rack and disconnected the power lead.

The green LED went dark.

For perhaps two seconds, the whole group seemed to pause. I do not know how else to put it. I was standing in the equipment-room doorway, but I could feel the collective expectation from everyone behind me in the corridor. All of us holding our breath, waiting for the noise to cease.

It did not.

Instead, it grew worse.

The numbers continued. The man's voice still came from the photocopier area, flat and rhythmic, but now I heard the sequence from somewhere else as well. Somewhere above us.

I looked up.

A ceiling vent was rattling slightly. Through it came the sequence, faint but distinct.

"6149027731. 480316592."

"You hear that?" Callum asked.

"Yes."

Then the light fitting began.

Not the tubes themselves. The electronic control gear produced the familiar hum of fluorescent lighting, except that it was no longer steady. It pulsed in the cadence of the numbers.

I stepped back into the corridor.

Helen was staring at the ceiling. Aisha had her notebook raised, but she was not writing. Tom had one hand on his radio.

The photocopier clicked.

It was not the normal mechanical noise of rollers moving paper. This was sharper and precisely timed. I counted the intervals without intending to and realised that each click fell exactly where a number belonged.

Tom's radio crackled. There was static at first, then something beneath it: one voice, perhaps, or several voices layered together and wrong.

Then the signal cleared and the radio began broadcasting the numbers in the same flat tone as the man beside the photocopier. The same perfect rhythm.

"6149027731. 480316592. 76104. 2259830. 4176."

It came through the speaker at Tom's shoulder as if the signal had been waiting for an open channel and had finally found one.

Tom seized the radio and turned down the volume. It made no difference. He changed channels.

The numbers followed.

He tried another. The same sequence continued.

"It's on every channel," he said.

His voice was tight.

The man by the photocopier turned towards us. He continued feeding blank sheets with one hand, but now held up the printed pages with the other, displaying them to us.

His identification card had swung round. I could read the name printed on it.

Graham Naylor.

His expression was not quite a smile. He looked pleased and intent, as though he had completed an assignment and wanted us to see that he had done it correctly.

That was when I felt the pressure return to my jaw. The urge to open my mouth and say the sequence aloud. To get it right. To match the rhythm exactly.

It frightened me more than the noise.

I took out the dark blue notebook Lucy had told me to keep. I turned to a blank square-lined page and wrote:

Strong impulse to repeat sequence. Involuntary. Feels like correction reflex.

My hand shook slightly, but writing helped. Putting it on paper made it external, something I could look at instead of something trying to force its way out.

"We need hearing protection," Helen said.

Her command voice had returned, but it was brittle around the edges.

"Now."

Callum had already removed his pack. He unzipped a side pocket and took out a box of yellow foam earplugs. He passed them round.

I took two, rolled them tightly between my fingers and inserted them. They expanded, reducing the volume.

Helen did the same. Aisha hesitated, still staring at Graham, then accepted hers. Tom inserted his one-handed while trying to switch off his radio with the other.

It helped.

For perhaps five seconds, it genuinely helped.

Then I felt the rhythm in the floor.

A structured vibration rose through the soles of my boots and into my legs. I shifted my weight. It remained there, steady and pulsed, timed exactly to the sequence I could now barely hear through the plugs.

The walls carried it too.

I placed my palm against the painted blockwork and felt it humming. It was not random. The same intervals travelled through the structure.

I took my ear defenders from my equipment bag. They were the kind I used in equipment centres or near high-powered transmission systems, rated at 31 dB. I put them on over the foam plugs.

The audible sound fell almost to nothing, but the vibration remained.

My jaw still wanted to move. My teeth tried to meet in rhythm. My tongue pressed against the roof of my mouth as though forming words I was refusing to say.

I looked at Aisha.

She stood beside Helen, still holding her notebook, and her lips were moving. She made no sound. She was only shaping something silently.

I watched for three seconds and realised she was counting, making the same sequence of mouth movements again and again.

6149027731. 480316592. 76104. 2259830. 4176.

She did not seem aware of it.

I decided we had to find the point where this had started. Some central source. If we could isolate it there, perhaps everything else would stop.

Helen gestured forwards.

Keep moving.

We went deeper into the building.

I opened my notebook and began tracking our route.

Left at photocopier. Twenty paces. Right turn. Fifteen more. Door marked SERVER ACCESS.

I wrote everything down because I did not trust my phone and needed something to do with my hands that was not counting numbers.

Framed photographs lined the corridor walls. Images of radio telescopes, nebulae and star fields. The sort of pictures one expected at an observatory.

I passed one showing the great dish illuminated at night, all white metal and geometric angles. I glanced at it as I walked.

In the glass, I saw my reflection move.

Then, roughly one second later, I saw it make the same movement again.

It was like a delayed video feed.

I stopped and looked directly at the glass. My reflection stopped too.

Then it stopped again, one second later, settling into position as though it had needed time to catch up.

That troubled me more than a little.

I forced myself to look away and wrote in my notebook:

Photo glass. Reflection delayed approx. one second. Reproduction effect or actual lag.

My handwriting was worse than usual.

I kept walking and did not look at any more photographs.

Callum reached the server-room door first. White vinyl letters, half peeled away, identified it. He pushed the door open, and we all felt the difference immediately.

The sound was cleaner inside.

I do not know how else to describe it. In the corridor, it had been muffled and layered, emerging from vents, walls, Graham's voice and Tom's radio. In the server room, it was sharper and more focused, as though the signal preferred dense electronics. As though it had found better speakers.

The room was narrow, about three metres by six, with server racks lining both walls. Much of the equipment was old: beige tower cases, dusty network switches and bundled cables secured to the rails. LEDs blinked in uneven patterns, green, amber and red.

The air smelt of warm plastic and ozone.

Callum stepped between the racks and placed a palm against one of the tower cases.

"It's vibrating," he said.

His voice was muffled by the hearing protection, but I understood him.

"Far too much. This isn't normal drive activity."

I moved closer. He was right.

I could see it. The entire rack shook slightly with a steady rhythmic hum matching the sequence intervals. The metal frame rattled against its mounting bolts.

Helen entered behind us, with Aisha close beside her.

"Shut it down," Helen said.

It was not a question.

Callum looked back at her.

"All of it?"

"All of it."

"This could be running active instruments, telescope positioning, environmental controls and data collection."

"I don't care," Helen said, her voice tight. "Shut it down."

Callum nodded once. He moved to the first rack and traced the cables, identifying each connection and its destination.

He was good at that. I had worked with enough electrical contractors to recognise the difference between somebody who merely pulled plugs and somebody who understood what he was doing.

He shut down the first rack in a controlled sequence, issuing soft shutdown commands through a terminal nobody had logged out of, then operating physical switches and finally isolating the circuit.

The LEDs went dark row by row. Fans wound down.

The numbers continued.

He moved to the second rack and repeated the process, controlled and methodical.

I appreciated that, although I already suspected it would not work.

Third rack. Fourth.

The room grew quieter as the equipment stopped, but the cadence did not change. It merely came from somewhere else.

The walls, perhaps. The floor. Inside my head. I could no longer tell.

When Callum isolated the final server rack, the room fell dark except for the glow from the corridor behind us.

The numbers did not stop.

Then another sound began.

It was a low undertone, deeper than the sequence. A bass vibration I felt more than heard. It placed pressure in my teeth. Not pain exactly, but a force that made my molars want to grind together, made my jaw want to clench and release in rhythm.

I wrote:

New undertone. Subsonic. Pressure in jaw and teeth after complete server-room shutdown.

Aisha made a small noise.

I looked towards her. Her phone was buzzing.

She pulled it from her jacket pocket and frowned. The screen illuminated her face. Notifications flashed across the display in rapid pulses.

"I don't have any service," she said.

She sounded confused, as though stating a fact that had ceased to make sense.

She tapped the screen and opened something. Her frown deepened.

"I didn't..."

Then she dropped the phone.

It struck the floor screen-first with a crack. Aisha recoiled as though it had burnt her.

"What is it?" Helen asked.

Aisha did not answer immediately. She stared at the phone on the floor.

"Drafts," she said at last. "Text-message drafts. I didn't write them."

Callum crouched, retrieved the phone and turned it over. The screen was still lit.

He looked at it for two seconds, then held it up for me to see.

The messaging application contained dozens of unsent drafts. There was no recipient selected. Every draft contained rows of the same numbers.

6149027731 480316592 76104 2259830 4176

The sequence repeated until it filled the screen.

"I didn't type that," Aisha said again.

Her voice was steady, but wrong. Too flat.

I believed her.

We kept moving. I do not remember who decided. Perhaps Helen made another hand signal. Perhaps we all understood that we could not remain in the dark server room with that undertone pushing into our teeth.

The corridor continued beyond it. There were fewer doors now and more photographs of the radio telescope along the walls.

I did not look at them.

We passed a toilet and a supply cupboard. Then the corridor widened into a small staff area with several chairs and a table. A counter ran along one wall, holding a coffee machine, a small fridge and a microwave.

The microwave was running.

I heard it first: the distinctive hum of the magnetron cycling.

I looked across.

The turntable was rotating beneath the lamp, but the microwave was empty. No food. Nothing on the glass plate.

The sequence was coming from it.

Not merely encoded in the hum. The numbers themselves came through clearly, as though the empty microwave were broadcasting them.

"6149027731. 480316592. 76104. 2259830. 4176."

Then I saw the woman.

She was sitting on the floor with her back against the counter, directly beneath the microwave. She wore an observatory polo shirt and dark trousers. Her chestnut-brown hair was dishevelled. Her eyes were half open, but she was not looking at anything.

Her identification lanyard lay across her chest.

Sophie Kershaw.

Her throat moved in small motions, as though she were trying to speak. Her mouth opened slightly. Her jaw shifted. Her throat worked.

No sound emerged. Or, if it did, I could not hear it through the microwave's broadcast, the other layers of the sequence and the undertone still pressing against my teeth.

"Hello," I said.

I moved closer and crouched to her level.

"Sophie, can you hear me?"

Her eyes tracked towards me. Slowly. As if the effort were enormous.

Her throat continued to move.

Tom came forward and crouched on her other side, trying to help without touching her too quickly.

I looked at her hands.

They were covered in small cuts. None appeared deep, but there were dozens of them, crossing her palms and fingers. They were fresh. Tiny beads of blood remained along several lines.

Then I saw the table.

Torn strips of magnetic recording tape were scattered across its surface. Brown tape of the sort used in old data-recording and reel systems, shredded by hand. It looked wet. Some sections clung together in dark clumps, while others lay in individual ribbons no wider than a lace.

Sophie's hands were still damp.

I understood that she had done it. She had ripped the tape apart with her bare hands, recently enough that the cuts were still bleeding. The edges were frayed where she had torn them, and the wounds across her fingers matched.

I opened my notebook and wrote:

Sophie Kershaw. Staff member unresponsive. Magnetic recording tape destroyed manually. Cuts to palms and fingers. Still attempting to speak.

Above her, the empty microwave continued turning beneath its lamp.

And it continued reciting the sequence.

Her throat kept moving. I still did not know what the tape had been, why she had destroyed it, or what she was trying to say.

Sergeant Tom Hargreaves moved before I could say anything about the tape or her hands. He simply stepped forward with the same police reflex I had seen when we first entered the building. Protect first, assess later. He crouched beside Sophie Kershaw and reached towards her shoulder, probably intending to check her pulse, get her attention or help her up.

The numbers became louder.

Not gradually. Immediately, as though someone had turned a dial. The volume went from barely manageable through the yellow foam earplugs and 31 dB ear defenders to something I felt throughout my skull. The undertones surged with it, creating pressure behind my eyes that made me want to squeeze them shut and keep them shut.

Tom's eyes widened. His hand froze about fifteen centimetres from Sophie's shoulder. Then his mouth opened and he began to speak.

"61490277314803165927610422598304176."

Fast. Far too fast. As though he were trying to finish the sequence before something stopped him. As though reaching the end mattered more than breathing, blinking or anything else.

His voice was not flat, as Graham Naylor's had been. It sounded urgent. Desperate, perhaps.

I took a step back without deciding to.

Helen Mercer moved faster. She seized the back of Tom's protective vest with both hands and hauled him away, her boots scraping across the lino. Tom did not stop.

He kept reciting, leaning forwards against her grip, his hand still reaching for Sophie even as Helen dragged him back.

"6149027731480316592..."

"Hargreaves, stop."

Helen's voice was sharp but controlled. A command voice.

"You need to stop talking."

He did not. He repeated the sequence continuously, returning to the beginning each time. His breath came in short gasps between groups of numbers. His free hand rose and reached for Sophie again, fingers stretching.

Helen pulled harder. Tom resisted, although it did not look as though he was fighting her. It looked as though he had somewhere he needed to be and she was standing in his way.

Driven. That was the word.

He twisted in her grip, trying to turn back towards Sophie, and I saw his face. His expression was neither angry nor frightened. It was focused. Intense. As though he had just remembered something critically important and, if he did not finish it at once, everything would fall apart.

Callum Price stepped in and caught Tom's other arm. Together, he and Helen dragged him back three full paces from Sophie. Tom's boots slid over the floor. Then he planted his feet and pushed forwards again, still reciting.

"7610422598304176."

That was when I noticed the sound coming from his chest.

Not his voice. Something else. A thin, crackling rendition of the sequence, slightly out of time with his mouth.

I stared at his vest and realised it was his body-worn video camera, the small black rectangle fixed to his left chest strap. Its microphone was covered. I could see the fabric of his uniform pressed against it. But it was broadcasting anyway.

The numbers emerged in a flat digital tone, layered over Tom's voice and producing an appalling doubled effect.

Dr Aisha Rahman had her notebook out. She was writing quickly. Her hand shook, but she kept going.

I looked back at Sophie. She had not moved. Her throat continued those small, silent motions. Her unfocused eyes tracked slowly between Tom and the rest of us.

Helen finally got Tom as far as the break-room entrance. He stopped forcing himself forwards, but he did not stop talking. The numbers continued without interruption, his breathing ragged between repetitions.

"Hargreaves."

Helen's voice hardened.

"Look at me."

He did not. His gaze remained fixed on Sophie.

I took out my dark blue hard-backed pocket notebook and wrote on the squared paper.

Proximity trigger. Attempted physical contact caused surge. H compelled to repeat sequence. Body-worn camera broadcasting despite covered microphone. Urgent compulsion observable.

My hand was shaking more badly than Aisha's.

Callum asked whether we should restrain him. Helen did not answer at once. I assumed she was making the same calculation I was.

On what grounds? Under what protocol? And what if restraint made it worse?

The volume began to fall, slowly, as though someone were easing the dial down again. Tom's voice became quieter, then stuttered, then stopped in the middle of a number.

He blinked. Looked at Helen, then Callum, then me.

His body-worn camera fell silent.

"What?"

He swallowed.

"What happened?"

Nobody answered immediately.

Helen released his vest but did not step away.

"Do you remember what you were doing?"

Tom looked past her at Sophie, still sitting against the counter.

"I was going to help her. She's..."

He stopped. His hand rose to his chest, fingertips brushing the body-worn camera.

"Did I...?"

"You repeated the sequence," Aisha said.

Her voice was quiet but steady. Clinical.

"For approximately forty-five seconds. You appeared unable to stop voluntarily."

Tom stared at her, then at me. I nodded.

"All right," he said.

He did not sound all right.

"All right."

I needed a plan. Something we could do instead of standing there and watching people break down one by one. I thought about the building's layout, what we had seen so far and what still made any kind of sense.

"The radio telescope," I said.

Everyone looked at me.

"The dish outside. We have to assume it's receiving something. That's what this place does. It receives signals, processes them and records them. If we can reach the main control room, we might be able to redirect it physically. Point it away from whatever it has locked on to."

Helen frowned.

"You don't know what it has locked on to."

"No," I admitted. "But it is a guess we can act on. Better than shutting down equipment that changes nothing."

Callum nodded slowly.

"Manual override. Azimuth and elevation controls. They should be in the primary operations room."

"Do you know where that is?" Helen asked.

"It should be central," he said. "Ground floor, possibly below us. It ought to be marked."

It was a guess. All of it. But it was something we might be able to control, or at least try to control, and that mattered more than waiting for the situation to worsen.

Helen looked at Sophie once more, then back at us.

"We move together. No one separates. Sergeant Hargreaves, you stay in the middle."

Tom opened his mouth as if he meant to object, then merely nodded.

We left Sophie there. I did not like it, but I could see no other option. Aisha hesitated in the doorway and looked back before following us.

The corridor beyond the break room felt wrong. I could not prove it. The walls were the same painted concrete block, the floor the same scuffed lino and the lighting the same mixture of working and dead fluorescent tubes. But the proportions were wrong. The corridor seemed longer than it should have been, not by much, only enough that I kept expecting to reach the next corner or doorway and had to take another three or four steps before it arrived.

I counted my paces, then stopped because I could no longer trust the count.

Callum walked ahead of me at a steady pace, checking doors as we passed them. The first on the left was a supply cupboard, with shelves of paper and toner cartridges. The second, on the right, was a single-cubicle toilet. Empty.

At the third door, he stopped and pushed it wider.

I looked past his shoulder and saw stacks of printed pages reaching from floor to ceiling. Every sheet was identical, covered in the number sequence. Tight rows. No margins. Exactly like the paper spilling from the photocopier Graham Naylor was feeding.

The stacks were neat and carefully ordered, as though someone had been filing them.

"That's a cupboard," Callum said.

"Yes."

"It shouldn't be."

He checked his mobile phone and frowned at a building plan that must have been cached.

"This should be an external emergency exit to the east car park."

I looked at the paper again. There must have been thousands of sheets, all carrying the same sequence, printed and stored.

"The building is insulating itself," Aisha said behind me.

She had stopped writing. Her notebook hung loosely from one hand while the cupboard lined its walls with the building's own output. That disturbed me more than it probably should have. It was not only the impossibility of it, but the implication that whatever was happening had continued for long enough to fill cupboards and replace emergency exits with storage.

We moved on.

The fourth door opened on to another cupboard and more stacks. The fifth was locked, although light showed beneath it. The sixth led to an empty office containing three desks and a whiteboard covered in equations I did not recognise.

The corridor turned left, then right, then left again. I lost track of the turns. Normally, my sense of direction was good. I had worked in enough government offices and equipment centres to navigate by exit signs and room numbers, but this building did not obey them. We should have looped back to somewhere familiar.

Callum stopped at a door marked PRIMARY OPERATIONS in stencilled lettering.

The sound changed. It became quieter.

For half a second I thought we had found shielding, perhaps conductive mesh or some other barrier capable of blocking the signal. Then I understood that it was not being blocked.

It was holding back. Waiting.

Callum pushed open the door.

The room was larger than I had expected, perhaps six metres by nine. Console desks lined three walls. Old cathode-ray monitors stood among newer flat screens, and equipment racks were packed with receivers, signal processors and patch panels. Four radio-room clocks labelled UTC, LOCAL, RECEIVER and ARRAY showed mutually incompatible times.

A broad window in the far wall overlooked the radio telescope dish. It was too dark outside to see much more than our own reflections in the glass.

One console in the centre remained active. A single monitor displayed a spectrum analyser: a bright, narrow carrier trace in the middle of an otherwise clean waterfall. It looked deliberate and precise. Not noise. Not interference. A signal.

Below it, a countdown was running.

00:12:48.

The final pair of digits began to descend.

47. 46. 45.

I stared at the display, counted backwards from ten in my head and pressed my thumb against my forefinger.

"Helen," I said.

My voice emerged more quietly than I intended.

"What is that?"

She did not answer immediately. She was looking at the same screen, her face arranged in the careful neutrality people adopt when deciding how much to reveal.

"Helen."

She took a breath and let it out slowly.

"An earlier team was sent here," she said, each word precise and controlled. "Last week. Two Ofcom officers from the Warrington office. A standard interference inspection, the same as this one. I waited, but they never checked back in. No calls. No reports. Their vehicle was found in the car park three days later. Empty."

Aisha turned to stare at her. Callum became very still.

"You knew that?" I said. "Before we came?"

"Yes."

"And you did not tell us."

Helen met my eyes.

"If I had, would you have come?"

I did not answer. Probably not. That was the honest answer, and she knew it.

Callum moved to the controls first. I did not see him decide. One moment he was standing still; the next he was reaching for the console panel containing the azimuth and elevation controls, with detents at five-degree intervals and manual override switches beneath them.

He switched both overrides and turned the azimuth control clockwise.

The motors responded. I heard them start through the floor, a low grinding whirr from somewhere outside or below us, and felt the vibration in the walls change.

For perhaps three seconds, I thought it might work.

Then the motor stopped in the middle of the movement.

Callum continued turning the control, but nothing happened. He tried the elevation system. Again, there was a brief response, then nothing.

I looked up at the spectrum display. The signal had been a narrow, concentrated spike. Now it was widening across the neighbouring frequencies. It was not weakening. It was adapting.

I wrote that down.

Trace broadening after dish redirection attempt. System compensating.

My handwriting had deteriorated. The letters leaned right, then left, with erratic pressure.

Aisha stood near the back wall, her notebook still in one hand. Her other arm was extended, the sleeve pushed up to the elbow. She held a black pen in her right hand and was writing on her left forearm.

Numbers. The sequence.

614902...

The digits formed in neat rows across her skin, running from the inside of her wrist towards her elbow. She was not looking at her arm. Her eyes remained fixed on the wall while her hand moved at steady, mechanical intervals, giving every number the same slant and pressure.

"Aisha."

She did not respond.

Tom released a sharp breath. I turned and saw him tear the yellow foam earplugs from his ears with both hands, quickly and almost violently. He dropped them on the floor and stepped towards a small rectangular speaker grille mounted beside a status board.

He leaned close. Too close. His ear was perhaps fifteen centimetres from the grille.

His expression was focused and desperate. Not frightened. Hungry for it. He needed to hear the numbers clearly, louder and more directly.

"Sergeant Hargreaves," Helen said.

Command voice again.

He did not move.

The undertone persisted, the low hum beneath everything. I felt it in my jaw and back teeth, pressure building. My teeth wanted to click together. They wanted to match the rhythm.

I took out my notebook and turned to the back page, where I had written Lucy Bennett's instructions six months earlier, during a counselling session after a bad week when I could not sleep and had counted ceiling tiles at 02:00 until my eyes burned.

Set a timer for ninety seconds. Pick your own interval. Breathe in for five counts. Hold for two. Breathe out for five. Let the count be yours.

I pressed the side button on my watch and cycled through its functions until I reached the timer. I set it to ninety seconds and pressed start.

The watch gave one quiet beep, just for me, and I felt the vibration against my wrist.

I breathed in.

One, two, three, four, five.

Held.

One, two.

Out.

One, two, three, four, five.

My rhythm. Not the building's. Not the sequence. Mine.

The pressure in my jaw eased slightly. It was enough.

I looked around the room. Helen was watching Tom. Callum was still at the controls, trying switches that refused to respond. Aisha continued writing on her arm, the pen travelling back towards her wrist now and filling gaps between the first rows of numbers.

Then I saw the power-distribution cabinet mounted low on the left wall. It had a brushed-steel door with black and yellow hazard markings along the edge, the sort used to feed monitoring systems, audio buses and secondary instrumentation racks. I had seen similar arrangements at mobile mast sites and radio facilities. They were normally sealed and tagged.

This one had a red plastic safety seal beside the latch.

The seal was broken. Half remained attached to the cabinet and the other half dangled from the catch.

I crossed the room. My watch beeped at the end of the ninety seconds. Without looking down, I reset it and continued breathing.

Five in. Hold for two. Five out.

I crouched beside the cabinet and pointed.

"Callum. What does this feed?"

He left the controls and crouched next to me. He examined the cabinet label, narrowed his eyes and read it aloud.

"PDC 7. Primary monitoring, audio buses A through D, secondary instrumentation."

"Key systems?"

"Yes. If you wanted something heard everywhere, this is where you would distribute it."

Helen was suddenly beside us. I had not heard her approach.

"Do not open that."

I looked up at her.

"We do not know what it powers," she said. "You could damage the equipment. There could be liability issues."

"The seal is already broken."

"That does not matter. We document it first, then we..."

I stopped listening.

Beyond her, Tom had placed both palms flat against the wall, one on either side of the speaker grille. His mouth was open and moving, forming the numbers. I could not hear his voice over the sequence from the ventilation system and the hum through the walls, but I could read his lips.

Six. One. Four.

"He is almost gone," I said.

Helen looked back at him. Her jaw tightened.

I opened the cabinet.

The door swung out on stiff hinges. Inside was a vertical row of circuit breakers, bundles of wire grouped with coloured ties, and a metal junction box at the top.

Fixed to the inside of the door at eye level with aluminium repair tape was an obsolete data-logging cassette. It was small, perhaps ten centimetres across, the kind once used for instrument archives. Its reels were visible through the clear plastic case.

Brown magnetic tape was wound tightly around the left spool and hung loose on the right. The reels were not turning, but I could feel movement from the cassette: a subtle pulse, a vibration.

The numbers sharpened inside my skull. They did not become louder. They became more distinct, as if they were sounding from within my teeth and the bones of my jaw.

I stared at the cassette and understood.

The radio telescope was not receiving the signal.

The building was playing it back.

Someone had embedded the recording in the distribution infrastructure and connected it to the systems feeding every speaker, monitoring circuit and audio bus in the control building.

A recording. Looping. Spreading.

I reached in and gripped the cassette by its rim. It was colder than it had any right to be. I pulled it free.

The aluminium tape tore away.

Helen said something behind me, but I did not process it. I turned and pushed past her, not hard, only enough to make room. She stumbled half a pace. I did not stop.

On the far side of the room stood a stainless-steel sink used for rinsing instruments and tools. Beside it was a small laboratory cryogenic flask containing liquid nitrogen, already open for some instrument-maintenance task. Vapour curled from its mouth.

I did not think about procedure. I did not think about what else might be inside it. I went straight to the sink, turned the cassette so that the reels faced down and forced it into the flask's opening.

It did not fit properly. I pushed harder. The plastic case cracked along one edge.

I kept hold of the rim, but freezing vapour engulfed my fingers and a brief splash of liquid struck the exposed skin. The cold became an immediate, savage burn. My fingers went numb almost at once.

I forced the cracked cassette farther into the flask, keeping as much of my hand clear as I could, and held it there.

My watch continued counting against my wrist.

Five in. Hold for two. Five out.

The signal fractured.

Tom screamed once, a sharp, high sound, then became completely silent. His body went rigid, his arms locked at his sides and his mouth stayed open.

Thin strands of brown magnetic tape slid from between his lips. They moved by themselves, wet and glistening, protruding roughly fifteen centimetres and trembling in the air.

Callum lunged towards him. He managed two steps before jerking backwards as though something invisible had seized him. His boots skidded across the lino. He tried to move forwards again and could not.

His mouth opened. Sound emerged, but not from him.

It came through the monitor speaker above the controls.

Callum's voice said, "6149027731."

His lips remained open and motionless.

The building had reassigned him. It had made him an output.

I looked at my hand, still gripping the cassette at its rim while most of the cracked case remained inside the flask. My fingertips were white and without sensation.

I checked the watch.

Forty seconds remained.

I kept the cassette down.

Helen was shouting something. Aisha had stopped writing and was staring at her arm, at the numbers covering her skin from wrist to elbow. She looked confused and appalled, as though she had only just noticed them.

The watch reached zero and beeped.

I pulled the cassette out by its rim.

It was frozen solid. Ice crystals coated the cracked casing. The reels were locked and the tape inside had become brittle. I could see fractures through the plastic.

The room went quiet.

Not silent. Quiet.

There was ordinary machine noise: the ventilation cycling, a faint electrical hum from the racks. The spectrum monitor displayed a flat trace where the signal had been.

But Callum and Tom remained standing. Both were rigid, their mouths open. The tape strands hanging from Tom's lips had stopped moving, although they trembled slightly with his breath.

Helen seized Aisha by the shoulder and pulled her towards the door. Aisha stumbled, still staring at her arm.

"We are leaving," Helen said. "Now."

I looked at the frozen cassette in my right hand. The skin of my fingers was red and beginning to blister. I still could not feel the injury.

I would later.

I carried the cassette with me.

Helen was already in the corridor, dragging Aisha after her. I followed.

Callum and Tom remained in the primary operations room. I did not know whether they could move. I did not know whether they were still themselves, or whether something else was standing there in their bodies.

We moved quickly. I counted the turns.

Right. Straight ahead. Left. Past the break room.

Sophie was still on the floor. We did not stop.

Past the server room and the corridor with the photographs.

I did not look at the glass. The reflections had been lagging behind us by roughly one second, and I could not bear to see what they were doing now.

We reached the main entrance. The keypad was still beeping at one-second intervals. Helen pushed open the door and we stepped outside.

The air was cold and clean. I dragged in a breath, and it hurt.

I looked back at the low brick control building. The lights inside began to pulse.

On for five seconds.

Off for two.

On for five.

The intervals matched my grounding rhythm exactly.

It had learnt my counter-rhythm.

Helen did not stop walking. She went straight to the white Vauxhall Vivaro with its discreet Ofcom markings, pulled open the driver's door and climbed in. Aisha got into the passenger seat, still holding her marked arm in front of her and staring at the numbers.

I climbed into the back and shut the door.

Helen started the engine and drove. Gravel, tarmac, trees. She did not stop at the gate or even slow down. She kept going until the secured Jodrell Bank technical compound was behind us.

Aisha took out her mobile phone and pressed the power button.

Nothing happened. It was switched off.

She stared at it.

Then I heard the sequence.

Faint and thin, coming through the phone's speaker grille even though the device had no power.

"6149027731 480316592 76104 2259830 4176."

With my left hand, I took out the dark blue notebook. My right still held the frozen cassette, and I could not feel my fingers.

I wrote everything I could remember.

Broken seal. Countdown beginning at 00:12:48. Magnetic tape. Obsolete data-logging cassette fixed inside the distribution cabinet with aluminium repair tape. Embedded playback. Callum's voice reassigned. Tom's mouth. The wet strands of tape. The building lights pulsing in my five-two-five rhythm.

I kept writing until we reached the main road, until my hand cramped, until the squared pages were crowded with details I did not want to forget and could not stop seeing.

Even then, after we had escaped the site, after the control building was kilometres behind us, after the spectrum trace had gone flat and the cassette had frozen solid in my burned hand, I could still feel it.

The sequence was vibrating in my teeth, waiting for me to resume the count.