The key Maren had obtained was old and heavy, the kind that opened industrial padlocks with the mechanical satisfaction of something designed to outlast the need that had created it. Crowe received it at half past ten on a corner two blocks from the factory, in an exchange that lasted forty seconds and involved no conversation beyond the essential.

  — Guard does his rounds at midnight — said Maren, handing over the key. — You have one hour.

  — Two — said Crowe.

  — One — Maren repeated, in the tone that meant there was no negotiation this time.

  Crowe took the key and left without confirming either number.

  The Industrial District at night was a different place from what it was during the day.

  During the day there was movement, noise, the human presence that made the environment merely uncomfortable. At night the closed factories revealed what the movement concealed — the true size of the structures, the weight of the idle machines, the sound that metal made as it cooled after hours of operation. A slow, irregular creaking, like bones settling.

  The mechanical components factory in the East Sector was called, according to the iron sign above the gate, Harwick & Sons — Precision Components and Assemblies. It was a long, low building of dark brick with an iron roof, no windows at ground level — only narrow slits on the second storey that during the day admitted enough light to work by and at night looked like half-closed eyes.

  Crowe opened the padlock on the side gate with Maren's key. Went in. Closed it behind him.

  The internal yard was small — just enough space for loading and unloading, with rails set into the ground for the transport platforms. There were two entrances to the building's interior: a wide loading door, locked with an iron bar, and a smaller side door that the key also opened.

  He used the smaller one.

  The factory interior was dark and tall.

  Crowe lit the hand lamp he had brought — small, regulated to the minimum useful light, enough to see without being seen from a distance. He raised it and stood still for a moment, letting his eyes adjust and the environment present itself.

  It was a single nave, long, with the ceiling at least eight metres up, supported by iron beams. Workbenches in parallel rows, each with specific equipment — lathes, presses, measuring instruments, tools organised on wooden panels on the wall at each station. At the far end, three larger machines that Crowe identified as hydraulic presses, with pipes connecting them to the building's steam system.

  Everything stopped. Everything in order.

  He started at the back and worked toward the front — his habit in large spaces, going to the point furthest from the exit first, so the way back was also the way of review.

  The hydraulic presses showed nothing of interest. Regular maintenance, fresh oil in the joints, pressure gauges at zero as they should be. The benches at the back were finishing stations — fine work, files and micrometric measuring instruments. Crowe moved the lamp slowly over each surface.

  He stopped at the fourth bench from the back.

  There were marks on the wooden top — not from tools, not from normal use. Circular marks, small, the kind a flat-based object leaves when placed repeatedly in the same spot. Three marks in a triangle, spaced with a regularity that ruled out accident.

  He crouched down. Ran a finger over one of the marks. Recent — the wood still had fresh compression, no dust had accumulated in the groove.

  Something had been placed there. Regularly. Recently.

  He stood and continued.

  The time clocks were near the main entrance — a row of six iron devices fixed to the wall, with registration cards stacked in a tray below each one. Crowe examined the devices one by one, starting with the first on the left.

  The mechanism was standard — internal paper roll, marking lever activated by inserting the card, manual winding to maintain movement. He opened the back panel of the first device with a thin instrument he carried in his pocket.

  The interior was correct. Mechanism in order, winding at proper tension, paper aligned.

  But there was something on the roll axle — a mark of recent adjustment. Small, nearly invisible, the kind a watchmaker or someone with similar training would leave when intervening in a mechanism with precision.

  Someone had opened these clocks. Had done something inside them.

  Crowe closed the panel. Opened the second. The same mark. The third — same mark, identical position. All six.

  He stood in front of the row of time clocks with the lamp in his hand, letting the new information settle.

  Deliberate intervention. Specialised. All six devices modified with the same technique, in the same position. It was not vandalism — it was work. It required knowledge of the internal mechanism of these specific clocks and access to the building's interior outside operating hours.

  This was a crime.

  A human crime, with a human motive and human execution.

  The disciplined voice in his mind said: there you are.

  The other voice went quiet for a moment — but did not disappear.

  Crowe returned to the centre of the factory. He stood between the rows of benches, lamp held low, thinking.

  There was a second component that Maren's report described and that the modified clocks did not entirely explain: the workers with no memory of their shifts. Modifying a time clock could falsify records — that was clear, it was the obvious explanation for phantom shifts on paper. But it did not explain why the workers themselves had no memory of the shifts.

  Unauthorized duplication: this tale has been taken without consent. Report sightings.

  Unless the workers had not done those shifts at all. Unless the records were entirely fabricated — not workers who had forgotten, but records that had never corresponded to any real presence.

  But the report said the workers were reporting a loss of memory. Not that they failed to recognise the records as theirs — they recognised them, but could not access the memory of what had happened during those shifts.

  There was a difference.

  Crowe began to walk slowly between the benches, the lamp sweeping the floor. He was looking for something without knowing exactly what — the kind of search that worked by exclusion, removing what was expected until what was not expected remained.

  He found it at the twelfth bench, in the central aisle.

  On the floor, partially beneath the bench, there was a vial. Small, amber glass, cork stopper still in place. Empty — or nearly so, with only a dark residue at the bottom. Crowe picked it up carefully, stopper down, and examined it against the light of the lamp.

  No label. Thick glass of laboratory rather than commercial use. The residue had the consistency of something that had partially evaporated — not spilled, evaporated. It had been opened in this environment and the contents had dispersed into the air.

  A chemical substance. Aerial dispersal. Workers with compromised memory of specific periods.

  The disciplined voice was firmer now: human crime. Human motive. Someone is using this factory at night and erasing the workers' memory so they don't report what they eventually notice.

  The other voice said, quieter but persistent: and the operative found at three in the morning inside a locked building with no explanation for how he got in?

  Crowe looked at the vial.

  It was a good question. He didn't have an answer yet.

  He pocketed the vial carefully, wrapped in his handkerchief to avoid contamination. He raised the lamp and made one more slow sweep of the space.

  That was when he saw the door.

  It was in the back wall, to the right of the hydraulic presses, partially concealed by a tool panel that had been positioned to cover it without blocking it completely. It was not in Maren's report. It was not on the building plan he had examined in the Guard's records before coming.

  It was a door that should not have been there.

  Crowe approached slowly. The door was iron, smaller than a standard door, with new hinges — the metal's shine was recent, no oxidation. There was a latch, also new, of the kind that opened from the inside without a key.

  He stood before it for a moment.

  There was no sound from the other side. No light visible through the gaps — the hinges sealed well. But there was something he identified after a second: temperature. The gap at the bottom released air slightly warmer than the factory interior.

  There had been recent activity on the other side. Or recent enough that the heat had not entirely dissipated.

  Crowe put his hand on the latch.

  And at that moment he heard footsteps in the external yard.

  Regular. Heavy. The guard on his rounds — earlier than Maren had promised, which was useful information about the reliability of Maren's promises in the context of industrial infiltration.

  He extinguished the lamp.

  The factory interior became completely dark — the kind of dark that has weight and texture, that presses lightly against the eyes as though the air itself had thickened. Crowe stood completely still with his hand still on the latch of the mysterious door, counting the footsteps outside.

  The guard stopped. There was the sound of a key in the padlock on the side gate.

  Crowe calculated: side gate, internal yard, smaller door, corridor to the centre of the factory. Forty seconds with a lantern, less if the guard knew the space.

  He had two options: leave through the loading door at the back — but it was barred from inside and the noise would be audible — or stay where he was and let the guard pass.

  He stayed where he was.

  The footsteps entered the yard. Stopped. The beam of a lantern more powerful than his swept the second-storey slits from outside — the guard was checking the building's exterior first. That bought more time.

  Crowe used the seconds to move — slowly, silently, with the familiarity of someone who had learned to move in darkness not through formal training but through repeated necessity. He went to the space between the last two hydraulic presses, where the shadow was deepest and the angle of view from the entrance was poorest.

  He stood completely still.

  The smaller door opened. The guard's lantern beam entered first, sweeping the floor, then the benches. The man came in — Crowe heard him more than saw him, heavy footsteps of thick-soled boots, the regular breathing of someone who did this every night and had long since stopped paying real attention.

  The lantern swept the rows of benches. Passed over the time clocks. Swept the back — close enough to the presses that Crowe felt the warmth of the beam without its reaching him.

  The guard stood still for a moment in the centre of the factory.

  Crowe did not breathe.

  Then the footsteps retreated. The smaller door closed. The side gate padlock closed.

  Silence.

  Crowe waited ninety seconds before moving. When he did, he moved slowly, lit the lamp at its minimum, and returned to the iron door at the back.

  His hand returned to the latch.

  This time, he opened it.

  The space on the other side was small — a narrow chamber, probably a former materials storage room, with a lower ceiling than the rest of the factory. It smelled of burnt oil and something else that took Crowe a moment to name: the same smell as the vial in his pocket. More concentrated, more recent.

  There was an improvised workbench. Equipment that did not belong to this factory — laboratory instruments, glassware, a small heating apparatus already cold but with its base still slightly warm. On the bench, handwritten notes on a sheet held down by a metal weight.

  Crowe moved closer. Read.

  They were formulae — chemical compounds, proportions, synthesis temperatures. There were margin annotations in small, hurried handwriting, the kind made during work rather than after. Technical terms he recognised from the vocabulary of experimental pharmacology, terms he had encountered in the chemistry volumes on his shelf at home but never in a practical context.

  It was an improvised laboratory. Someone was synthesising something here, at night, using the factory as cover.

  In the corner of the chamber was a wooden crate. Crowe opened it.

  Inside, in vials identical to the one he had found on the factory floor, were twelve more units. All with the same dark residue, all without labels, all with the cork stoppers characteristic of non-commercial laboratory glass.

  He closed the crate. Looked at the bench. At the formulae. At the still-warm heating apparatus.

  The disciplined voice in his mind had gone quiet some minutes ago — not because it was wrong, but because the evidence had reached the point where it no longer needed defending.

  This was a crime. A careful, methodical crime, with resources and specific knowledge. Someone was producing a substance capable of impairing short-term memory, dispersing it into the factory air during night shifts, and falsifying attendance records to cover the use of the space.

  There was a motive. There was a perpetrator. There was physical evidence.

  It was investigation. It was deduction. It was the kind of problem Crowe knew how to solve.

  But there was still the operative found at three in the morning. Inside a locked factory. With no explanation for how he had got in.

  Crowe looked around the chamber. At the brick walls, the low ceiling, the stone floor. No window. A single door — the one he had opened.

  There was no other entrance.

  So how had the operative got in?

  The other voice — the more recent one, the less trained one — said something he did not like hearing but could not dismiss:

  What if he hadn't got in?

  What if he had arrived from somewhere else?

  Crowe stood in the chamber for a moment with that question.

  Then he pushed it firmly aside. There was work to be done before speculation — the vial in his pocket needed analysis, the formulae needed copying, Maren needed a report he could use.

  He took the notebook from his inside pocket and began copying the formulae.

  The headache returned while he wrote — behind the left eye, as always, but deeper this time. As though he were somewhere he was not meant to be and his body had chosen this particular way of communicating the fact.

  He ignored it. Kept writing.

  Londrivar ground away outside, indifferent as ever.

  And in the improvised chamber, lit only by Crowe's lamp, the formulae for something that erased memory waited patiently to be understood.