The city did not exist, not really — not from where Cael Morrow sat.

It existed in resolution: three hundred and twelve frames of it, tiled across the wall of monitors that faced his desk like the stained glass of some mechanical cathedral. Feed Seven showed the Ashburn Viaduct at quarter-past-six in the morning, the gaslight mantles still burning amber against the pearl-grey murk. Feed Nineteen was the Irongate Wharf, the tall cranes motionless, their arms raised in permanent supplication. Feed Forty-One: the Corben Street crossing, where a flower-seller had already arranged her carnations in buckets and stood blowing into her cupped hands, waiting for the city to remember her.

Morrow watched the flower-seller for a moment. He did this sometimes — chose one figure from the feeds and followed them across the morning, watching the small mechanics of a life proceeding without any awareness of him. It was, he had decided, not voyeurism. It was calibration. It reminded him that the city was still moving.

He himself had not moved. Not outside. Not for nineteen months.

* * *

The office was on the fourth floor of a building that had no plaque and no number, because Cael Morrow did not want clients finding him by accident. The ones who came to him came because they had been told, by someone who knew someone, that there was a detective on the upper floor of the building beside the old Pressmann Foundry — the one with the dark windows — and that he was expensive, and peculiar, and that he was very rarely wrong.

The dark windows were reinforced with boiler-plate steel behind the glass. The glass itself was three-pane, sealed with rubber gaskets that Morrow replaced every four months. The building's original ventilation ducts had been torn out and replaced with a system of his own design: air drawn through a series of filter housings packed with activated charcoal and fine copper mesh, the whole apparatus driven by a pair of small steam-powered fans that sat on the roof in their own insulated casings, their pressure gauges visible through the port-glass he had mortared into the ceiling of the kitchen alcove. He checked those gauges every morning. He checked them twice.

The air inside was his air. He had made it that way.

He had also made the light. Six gas lamps, each in a ceramic housing, each with a precision-ground lens that spread the flame into something closer to daylight. He had read somewhere — a physician's monograph, one of the stacks — that the quality of artificial light affected the calibration of the eye. He had believed it immediately, the way he believed most things he read in physicians' monographs, because physicians were the only writers who understood that imprecision had consequences.

The rest of the room was orderly in the way that a workshop is orderly: everything placed according to function rather than appearance. A long oak table dominated the centre, its surface covered with the overlapping rings of a thousand cups of tea and the occasional ink-stain that had been blotted but not erased. Two filing cabinets, both locked. A card-index cabinet, unlocked, accessible, the cards themselves written in Morrow's compressed and slightly tilted hand. A leather chair, dark brown, cracked along the right arm, that had been in the office when he took the lease and that he had kept because removing it would have meant propping the door open and he did not prop the door open.

And the monitors. Always the monitors.

He had built the surveillance network himself, over the space of eighteen months before the accident, and had expanded it in the nineteen months since, because he had nothing else to do with his hands and expanding the network was the only form of leaving the building that remained available to him. He had contacts at the Exchange telegraph office, at the Municipal Gaslighting Authority, at three separate private courier firms, and at the Ashburn Constabulary — the last relationship strictly informal and entirely unacknowledged by both parties. Through these contacts he had arranged camera placements at forty-seven points across the city. The cameras were his own design, daguerreotype-adjacent but faster, fitted with pneumatic shutter mechanisms that fired every eight seconds and transmitted the image to his receivers via wire. The receivers developed the image chemically and projected it onto the monitor screens via a system of lenses that he had taken three months to calibrate and that he recalibrated every six weeks.

Three hundred and twelve feeds. He could not watch all of them at once. He did not try. He let his eyes move across the wall the way a man reads a page — not every word, but enough to know if something had changed.

This morning, nothing had changed. The flower-seller on Corben Street had sold two carnations. The Ashburn Viaduct was empty. Feed Eighty-Eight showed the narrow passage behind the Meridian Hotel, where the bins were set out and the kitchen porters came to smoke between services. A cat was sitting on one of the bins. Morrow noted it and moved on.

He poured his third cup of tea.

* * *

The accident was not something he discussed. It was not something he had named, in his own mind, beyond the accident, because giving it a more specific name would have made it a story, and he had found that stories had a way of demanding to be told, and he had no one to tell it to and no desire to begin.

What he would have said, if he had been the kind of man who said things, was this: there had been a case. It had seemed, at the time, manageable. Most cases seemed manageable at the time — that was the nature of cases, the seductive clarity of a problem that appears bounded. The case had not been bounded. It had opened, the way certain wounds open, into something larger and more serious than the surface suggested, and by the time he understood what he was actually inside, it was too late to extract himself cleanly.

He had survived. This was not nothing. He reminded himself of this with some regularity.

But the surviving had come at a cost that was not, he had found, the kind of cost that could be paid once and discharged. It was the kind that accrued. That presented itself, at unpredictable intervals, in the form of a sensation he had not had a name for until a physician — a different physician, a real one, encountered once in the months immediately after — had given him one. The physician had called it a sensitisation of the threat-response and had drawn, on the back of a prescription form, a small diagram of a nervous system to illustrate his point. The diagram had been quite good. Morrow had kept it.

What it meant, practically, was that the outside was no longer navigable. Not consistently. Not in the way that work required.

And so he had built the network. And so the office was sealed. And so he had made the air his own.

This was not defeat. He had decided this early and stuck to it with some determination. It was adaptation. It was the application of the same intelligence that had always served him to the problem of his own particular constraints. He had read, in one of the stacks — a different monograph, engineering this time — that the best solutions were not the ones that pretended the obstacle was not there, but the ones that incorporated the obstacle into the design.

He had incorporated the obstacle.

He was, in most respects that mattered, still a detective.

* * *

The case arrived at half-past-seven.

It arrived in the form of a pneumatic message cylinder — the matte-black type, the one that meant the sender had paid for the diplomatic-grade confidentiality seal — which came up through the speaking-tube post with a soft thud and settled in the brass receiver beside Morrow's right elbow. He looked at it for a moment without touching it. He did this with all correspondence. It was a habit formed from the same instinct that made him check the air gauges twice.

Then he picked it up, broke the wax seal — a compass rose, which was either genuinely navigational in significance or was someone's idea of a portentous affectation — and extracted the message form within.

The paper was good. Heavy stock, cream-coloured, the kind used by solicitors and private banking houses. The writing was copper-plate and extremely even, which meant either a professional copyist or a person who had spent a great deal of time learning to disguise the natural character of their hand. He noted both possibilities and held them loosely.

The message read:

Mr. Morrow — I require your assistance in a matter of considerable delicacy and corresponding urgency. A thing has been taken from my household. Its value is not monetary, though the monetary value is itself not inconsiderable. I am told you do not meet clients in the conventional manner. I am told you have, nonetheless, a method. I am prepared to accommodate whatever arrangement you require. Please indicate your terms and I will send a full account of the matter by return. — V.A.R.

He read it twice. Then he held it up to the nearest lamp and examined the paper against the light. Watermark: a sheaf of wheat inside a circle. He knew that mark — it was used by Helwick & Sons, stationers on the Crescent, who supplied exclusively to the upper professional tier and to six or seven of the old merchant families. That narrowed the field considerably but did not close it.

V.A.R. Three initials. The last name initial R.

He set the paper down and turned to the card index. He pulled the R-drawer and worked through it methodically, not rushing. Rushing the index was always a mistake. After four minutes he had three candidates who matched the watermark and the probable social register: Rhastan, Voyle, of the Harbour Authority board. Ryemoor, V.A., a widow of the Ryemoor textile family, residence in Candover Square. And a third — a note he had made eight months ago from an item in the commercial pages — Ratchford, V.A., trading partner of the Caldenmere Mechanism Works, the precision instrument manufacturer on the south side of the Ashburn district.

He pulled up Feed Sixty-One, which covered the Candover Square approach. Feed Sixty-One showed a townhouse at the far end of the square — one of the old ones, the kind with the ironwork balconies and the stone facing that had been black with soot for so long that cleaning it would have constituted a kind of fraud. There was a light in the first-floor window. Someone was awake early, or had not yet gone to bed.

He replaced the cards. He would not decide between the candidates yet. He needed more information, and more information was what the robot was for.

* * *

He had not named it. He had tried, once, and the names he produced all seemed either mocking or sentimental, and both felt wrong for the same reason: the robot was a tool, and tools did not have names. What he called it, when he thought about it at all, was the robot, or the unit, or occasionally — in a moment of insomniac candour that he preferred not to examine — the legs.

It stood in the alcove off the main room, behind a door that was itself sealed with rubber gaskets, because he did not see why the robot's alcove should be any less controlled than the rest of the environment. It was approximately human in proportion — he had designed it that way deliberately, on the theory that a humanoid figure attracted less attention in a city street than any of the alternatives — but the resemblance was imprecise in ways that were, he had found, both unavoidable and useful. The face was a smooth oval of brushed copper, the features suggested rather than sculpted: the shallow rise of a nose, the slight indent that might be read as a mouth, the two camera-lenses set where eyes would be, each mounted in a gimbal housing that allowed them to track independently. The body was jointed brass over a steel armature, the joints packed with graphite-impregnated felt that reduced both friction and noise. The hands were his best work: five-fingered, each finger independently articulated, the grip-pressure adjustable by a dial set into the right forearm.

It was not alive. He was quite clear on this. It processed instructions transmitted via the telegraph wire he had run from his desk to the alcove, translated them into movement via a system of pneumatic actuators, and reported back through a second wire that carried sensory data — pressure, temperature, the optical feed from the camera-lenses — to the receiver bank at his desk. It did not think. It did not feel. It was a very sophisticated extension of his reach.

He told himself this with some regularity.

He crossed to the alcove door and unlatched it. The robot stood in the darkness in its usual posture — weight centred, arms slightly forward, the posture of a thing waiting without impatience because it had not been told what to be impatient about. Morrow examined it briefly. He checked the hydraulic pressure gauge on its left thigh panel: nominal. He checked the optical feed by pulling up the receiver on his desk and confirming the image matched what he could see with his own eyes when he stood where the robot stood. It did.

He returned to his desk and sat down.

He drafted the reply to V.A.R. first: acknowledgement of receipt, a statement of his daily rate, a request for a full written account of the matter by noon. He sent it via the speaking-tube post in a plain cylinder, no seal — he was not a man for portentous affectations.

Then he turned to his operator's board — the array of telegraph keys and dials that translated his inputs into the robot's movements — and began to compose the morning's instruction set.

The unit was to proceed out of the building via the service entrance on the ground floor. It was to make its way to three locations: the Helwick & Sons stationery on the Crescent, the Candover Square townhouse of the probable V.A. Ryemoor, and the commercial office of the Caldenmere Mechanism Works. At each location it was to observe and record. It was not to draw attention to itself. It was not to interact with anyone unless directly addressed, in which case it was to use the pre-loaded response set: minimum words, neutral affect, the name Morrow had told it to use, which was simply Unit, because he had found that people, when confronted with the unexpected, defaulted to courtesy if given something to address.

He ran the instruction set twice through the verification sequence. Both times it returned clean.

He sent the activation signal.

He watched through the optical feed as the robot moved. He had been watching this for nineteen months and it still struck him, each time, as a thing slightly difficult to name: the movement of a body through space that was not his body but was, in every practical sense, his eyes. There was a word for it in the physician's monograph he kept. He did not use the word.

The robot crossed the alcove, opened the inner door — Morrow had fitted it with a handle the robot's hands could operate — and moved into the service corridor. The optical feed tilted slightly as it descended the stairs: the gimballed camera-lenses adjusted, the image steadying. The ground floor was dark at this hour, the building's other tenants not yet in. The robot navigated without a lamp because its camera-lenses processed in the near-infrared spectrum, which Morrow had found more reliable than the variable quality of street-level gaslight.

The service door at the back of the building was secured with a bolt that he had modified, eighteen months ago, so that the robot could throw it from the inside.

The robot threw the bolt.

The robot opened the door.

The morning air came in — cold, carrying the smell of coal smoke and river water, the particular compound scent of the city before it had fully woken — and for a moment, through the optical feed, Morrow could see the alley behind the building: the wet cobblestones, the grey sky between the rooflines, the cat from Feed Eighty-Eight sitting on a doorstep three buildings down and watching with the supreme indifference of its kind.

Then the robot stepped outside.

And something moved.

It was not on any of his feeds. It was in the alley itself — a figure, standing in the shadow of the opposite building's loading dock, which was the one blind spot he had not yet managed to cover. The figure did not run. It did not hide. It simply turned, with the slow deliberateness of something that had been waiting, and looked directly at the robot.

Or rather: looked directly at the camera-lenses, as though it knew, precisely, where to look.

The optical feed transmitted the figure's face for exactly three seconds before the angle shifted and it was lost.

Morrow replayed those three seconds four times. The face was male, middle-aged, weathered in the way of men who spent time outside in difficult conditions. The eyes were pale — grey or light blue, the feed's resolution did not distinguish. The expression was not threatening. It was not surprised.

It was, Morrow decided, on the fourth replay, recognitive.

The figure had been waiting for the robot. And when the robot appeared, the figure had looked at it with the specific expression of someone who sees a thing they have been expecting arrive exactly on schedule.

Morrow's hand hovered over the telegraph key that would bring the robot back inside.

He left the hand hovering for six seconds.

Then he sent the instruction to continue.

He sat back in his chair, in his sealed room, with his filtered air and his three hundred and twelve feeds, and he watched the optical feed as the robot moved down the alley toward the street, and he thought about a figure that had known exactly where to look.

Outside, on the cobblestones, the city was waking up. The flower-seller on Corben Street had sold another carnation. The cranes at Irongate Wharf were beginning to move. The gaslight mantles on the Ashburn Viaduct were flickering out one by one as the dawn came up, tentative and grey, over the rooftops of a city that Cael Morrow had not walked in nineteen months.

He watched the feed.

He waited.