Crowe woke late.

  Not from tiredness — the rib had made sleep intermittent, waking him three times with the kind of dull ache that was not urgent enough to demand action but consistent enough to prevent proper rest. He woke the fourth time and decided he was finished trying.

  It was nine in the morning. From the sound rising from Copper Street — the specific whistle of a steam valve that needed adjusting at the corner of number eight, which had needed adjusting for six months and continued to need it — Londrivar was already in full operation.

  He lay still for a moment looking at the ceiling.

  There was no case.

  It was a condition most people would call rest and that Crowe called an interval — and which, given recent circumstances, he had begun to use with more care than before.

  He got up. Went to the window.

  Copper Street in the morning had a different quality from the evening — the steam was thinner, the fog had retreated to the lower streets, and Londrivar's grey light arrived without enough obstruction to be called brightness but with enough presence to be called day. The copper pipes on the facades of the surrounding buildings sweated condensation that ran down in irregular lines, and the few people passing walked with the particular determination of those who had a destination and preferred to reach it without conversation.

  Crowe stood at the window with his coffee for a moment.

  Then he picked up his coat.

  There was no destination. That was the point.

  He had learned — late, against the resistance of a mind that always preferred structure to its absence — that certain kinds of processing only happened in purposeless movement. Resolved cases, pending cases, fragments without adequate folders. The mind worked in the background when the foreground was occupied with the simple act of walking.

  He started in Lower Londrivar because that was where his feet went without consultation.

  Lower Londrivar in the morning was the city being itself without an audience.

  The markets opening with the efficiency of those who had done it every morning long enough for the process to be muscle rather than thought. Vendors arranging stalls with products that Crowe identified by smell before sight — salted fish, spices of improbable provenance, the hot metal of freshly forged tools being sold by someone who had forged them that morning or was pretending they had. Children who should have been somewhere else doing exactly what children do when they are somewhere else without supervision.

  Crowe walked without stopping, hands in his pockets, observing with low attention — not investigation mode, which was high and costly, but existence mode, which was distributed and free.

  He passed Ironmongers' Street.

  Voss's shop had the window repaired — someone had put in new glass, smooth, without the diagrams that had been destroyed on the night of the disappearance. The bronze plaque remained — A. VOSS — WATCHMAKER AND PRECISION INSTRUMENTS. The bottom line, in smaller letters: Time-related matters in general.

  The shop was closed. It would remain closed, probably, until someone from the family Maren had said didn't exist appeared to claim the space, or until the building's owner made a decision about what to do with a ground-floor unit whose tenant had vanished without leaving a forwarding address.

  Crowe stopped on the pavement for a moment.

  There was something different about the shop. Not the window, not the door — the pavement in front. A mark on the dark stone paving that he had noticed on the night of the first visit as a minor data point and which now, with the accumulated context of two cases and a hundred-year-old folder, drew different attention.

  It was a specific kind of wear — not the kind that time and foot traffic produce, which was irregular and distributed. It was circular wear, the kind that happens when something is placed regularly in the same spot. A round base, approximately thirty centimetres in diameter, slightly concave at the centre.

  Something had stood there. Repeatedly. Long enough to leave a mark in the stone.

  Crowe crouched down. Ran his fingers over the mark. The stone was smoother inside the circle than around it — polished, almost. The kind of polish that comes from prolonged contact with metal.

  An instrument. Something on a tripod or circular base, positioned at that specific point on the pavement in front of Voss's shop.

  Calibration of an unconventional measuring instrument.

  The nameless entry in Voss's notebook. Mourne. The instrument he had commissioned and which had been incomplete when Voss disappeared.

  But the mark on the pavement was outside the shop — not inside. Someone had used an instrument in front of the shop, not within it. Which was different from calibration. Calibration happened indoors, under controlled conditions.

  This was field measurement.

  Crowe crouched on the pavement looking at the mark for a moment. Around him Londrivar continued — the vendors, the steam, the distant whistle of a rail carriage. No one looked at a man crouching on the paving with more than the one second of attention that anything slightly out of the ordinary received before being filed as not relevant.

  He took out the notebook. Made a sketch of the mark — diameter, shape, degree of polish, exact position relative to the shop door.

  He put the notebook away. Stood.

  He would record the data. For now that was all it was — a data point without an adequate folder, the kind that Ashcroft had spent twenty years accumulating because there was nowhere to put it but also no reason to discard it.

  The fog had returned when he reached the boundary between Lower Londrivar and the Industrial District.

  He hadn't planned to go there — it was where his feet had gone, which was the point of the exercise. He stood at the boundary for a moment looking at the gradual change of landscape — the buildings growing taller and more closed, the streets narrowing, the smell of oil and metal replacing the smell of wood and food.

  The District in the morning had a quality it didn't have at night — not of danger, but of absolute indifference. The machines operated without comment about who was around. The workers moved along routes they had taken hundreds of times and which therefore required no more conscious attention. It was a neighbourhood that had become so entirely itself that it no longer needed effort to exist.

  Crowe went in.

  He walked along two streets without direction and then turned into one he had seen before — on a map, in a report, in a context that took two seconds to access.

  It was one of the streets from the disappearance list.

  Not the exact address — the exact address was halfway down the block ahead, in a grey brick townhouse with iron pipes on the facade and a third-floor window with the curtain slightly open. It had been the twelfth case on the list. A woman, thirty-eight years old, had disappeared from that flat sixteen years ago. The report was brief — less than a page, the kind of brevity that suggested either investigative incompetence or an active interest in not going deeper.

  Crowe stood on the pavement in front of the building.

  He had passed through this street before. He was certain of it — there was a quality of recognition that was different from general familiarity with the city, it was specific, anchored in a concrete moment. But he could not access when. The memory was there — present, with texture — but without date, without context, without the framing that made a recollection usable.

  The tale has been taken without authorization; if you see it on Amazon, report the incident.

  He stood looking at the third-floor window for a moment.

  The slightly open curtain moved — an interior draught, an imperfect window, the kind of thing that happened in old buildings all the time and meant nothing.

  Crowe registered the movement all the same.

  He kept walking.

  Ashcroft had sent a note.

  It was folded under the flat door when he returned shortly before midday — precise handwriting, good-quality paper, no greeting.

  Crowe — I have found three more references to the symbol in documents I had not previously connected. All of them predate the material I have already shown you. If you come this week, I will bring everything together. There is something I need to show you in person — it should not be sent by note. — A.

  Should not be sent by note was a phrase Ashcroft had not used before, which gave it specific weight. The archivist was a man of precision — if he had chosen to say it that way, there was a reason for the choice.

  Crowe placed the note on the table. Looked at it for a moment.

  Then he looked at the corkboard.

  The fragments from Case 001, those from Case 002. The sketch of the symbol with the number three from the Institute table. The list of twenty-four disappearances. Pell's notes on Vex's compound. The copy of the formulae from the improvised laboratory.

  And now, in an empty corner that had been waiting: the sketch of the circular mark on the pavement in front of Voss's shop.

  He had been adding data without noticing he was adding it. It was the mode of functioning he feared most — when investigation happened without conscious supervision, when connections formed before he could verify them.

  But the connections were there.

  He took the cigarette from his pocket. Lit it. Stood before the corkboard with the smoke rising slowly and the rib protesting with each deep breath.

  Someone knocked at two in the afternoon.

  Three knocks — not Maren's rhythm. Lighter, more irregular, with the spacing of someone who had decided to knock and then reconsidered partway through and continued anyway.

  Crowe opened the door.

  Owen Alexander was in the corridor with the leather case in his pocket and the expression of someone who had planned a reason to appear and was assessing, in the first few seconds, whether the reason was sufficient.

  — The cut — he said. — I needed to check whether it was inflaming.

  — It isn't — said Crowe.

  — I can verify that myself.

  Crowe stood in the doorway for a moment. Then stepped back and let him in.

  Owen entered with the quality of someone observing a new space — not with Crowe's calculating assessment, but with the genuine attention of someone interested in what the environment says about the person. He looked at the corkboard with the fragments and the notes. At the bookshelf with the chemistry volumes beside the violin. At the bench with the compounds. At the worn armchair by the window.

  He didn't comment on anything. Which was, in itself, a comment.

  — Sit — said Crowe, indicating the visitor's chair.

  Owen sat. He examined the cut with the same clinical efficiency as the previous evening — two fingers, specific pressure, observation of the colouring around it. Satisfied with the result of the inspection, he leaned back.

  — It's not inflaming — he said.

  — I said that before you came in — said Crowe.

  — I know — said Owen. With the simple honesty of someone who didn't bother to pretend that the stated reason was the real one.

  They were quiet for a moment. Outside, the valve at the corner of number eight whistled for the tenth time that day.

  — The board — said Owen, looking at the cork. — Those are the cases.

  — They are.

  — The symbol that repeats — said Owen, looking at the sketches. — I saw it three times in different positions.

  Crowe looked at him.

  — You looked carefully — said Crowe.

  — I walked into a room with a board covered in information — said Owen. — It would have been difficult not to. — A pause. — I'm not asking about the content. Just observing that there's a repeated visual pattern.

  — There is — said Crowe.

  Owen looked at the symbol for a moment longer. Then he stepped back from the board with the deliberate gesture of someone establishing a boundary — I saw it, I noted it, I won't press — which Crowe recognised as a form of respect.

  — How long have you lived here — said Owen.

  — Four years.

  — And Mrs. Hadwell — said Owen, with a vague gesture toward the ground floor.

  — Since the beginning — said Crowe. — How do you know her name.

  — She opened the door when I arrived — said Owen. — She asked my name, verified that I had been invited, and told me the flat was on the third floor but that the fourth step and the seventh creak and that if I was going to wake the building she'd prefer to know in advance.

  Crowe was quiet for a second.

  — She let you come up — he said.

  — She did — said Owen. With the corner of the mouth that was his dry humour being exercised. — Which I think means something, though I'm not certain what.

  Crowe looked at the closed door for a moment.

  Mrs. Hadwell had let in exactly two people without his having given advance notice in the four years he had lived there. The first had been Maren, in the first month, after a case that had ended at three in the morning and had required a conversation that could not wait. The second was now.

  He didn't develop the data. He filed it.

  — Where do you live — said Crowe.

  — Two blocks north — said Owen. — Above the practice where I work. — A pause. — Convenient and cheap, which are the two qualities a medical assistant with family debts can prioritise simultaneously.

  — The debts — said Crowe.

  — Being paid — said Owen. In the voice of someone who had reached an agreement with a difficult situation and had decided the agreement was sufficient. — Slowly. But being paid.

  Crowe went to the kitchen. He returned with two glasses of something that was not tea and not coffee and that Mrs. Hadwell had left outside the door a week ago with a note saying for days with a damaged rib, which had raised questions about how much she heard through the ceiling that Crowe had decided not to investigate for reasons of mental health.

  He handed one to Owen without asking if he wanted it.

  Owen drank. Made an expression.

  — What is this — he said.

  — I don't know — said Crowe. — Mrs. Hadwell makes it.

  — And you drink it.

  — It works for a damaged rib — said Crowe.

  Owen looked at the glass. Took another sip with the resignation of someone accepting that certain things didn't need explanation to be useful.

  They stayed a while longer in the flat. The conversation followed the pattern from the previous evening — fragmented, honest, with silences that neither of them treated as a problem. Owen asked about the violin. Crowe answered in a way that was sufficiently vague to be technically true. Owen didn't press.

  At some point Owen looked at the corkboard again.

  — The symbol — he said. In the voice of someone who had decided to ask a question they had been keeping back. — It appears in both cases.

  — It does.

  — And you think it's going to appear in the next ones.

  Crowe was quiet for a moment.

  — I do — he said. Which was more than he had said to Maren on the subject and less than he knew, which was the approximate balance of honesty he had found for the topic.

  Owen looked at the symbol for a moment longer.

  — If it does — he said, in the careful voice of someone constructing a sentence they had planned in advance — and if you need someone who won't ask questions you don't want to answer but who shows up when it's useful —

  — Alexander — said Crowe.

  — I'm offering — said Owen. — Not asking.

  Crowe looked at him.

  Owen held the gaze with those pale green eyes that paid genuine attention and which contained, as far as Crowe could read, no agenda beyond what had been said.

  — Why — said Crowe.

  Owen was quiet for a second. Then:

  — In the cellar last night — he said. — When the four men appeared. I was in the pub but I hear when the dynamic from downstairs changes. I went up to the entrance and stood at the top of the stairs. — A pause. — I saw enough to know that what you did has no explanation I can give with the vocabulary I have.

  Crowe was completely still.

  — And — he said.

  — And I have a question I can't let go of — said Owen. With the simplicity of someone delivering a truth they hadn't embellished because there was no point in embellishing it. — Not about the cases. About what I saw. — He looked at Crowe with an attention that had shifted slightly in quality — not suspicion, but the recognition of something that didn't yet have an adequate category. — I've always been better at questions than at accepting there's no answer.

  The flat was silent for a moment.

  Outside, Londrivar groaned and smoked with its customary indifference. The valve at number eight whistled again. Somewhere on a floor below, Mrs. Hadwell moved with the particular footsteps of someone doing something else but peripherally paying attention.

  Crowe looked at the corkboard. At the symbol. At the list of disappearances. At Ashcroft's note about what could not be sent by note.

  — Next time there's something — he said, at last. — I'll let you know.

  It was not a complete invitation. It was not a refusal. It was the exact distance that existed between trusting someone and not yet knowing whether it was safe to do so.

  Owen nodded once. Without pressing for more — which was, Crowe noted, exactly the right response.

  He stood. Picked up his coat.

  — The Crooked Crow — he said, at the door. The same as the night before, with the same quality of a joke that was not entirely a joke.

  — Good afternoon, Alexander — said Crowe.

  Owen went down. The fourth step creaked. The seventh too.

  Crowe stood in the middle of the flat for a moment.

  Then he went to the corkboard and stood looking at the circular mark he had sketched — the pavement in front of Voss's shop, the polished stone, the instrument that had stood there repeatedly.

  There was something in that data he hadn't yet developed. A connection that was formed but that he hadn't fully examined — the kind the mind produced in the background and that surfaced when there was enough space for it.

  The mark was circular. The diameter of an instrument base for field measurement.

  Mourne had said the instrument Voss was calibrating was to detect proximity to discontinuity. Not to create it — to detect it.

  Someone had been using an instrument in front of Voss's shop before the disappearance.

  Measuring.

  Which meant that someone had known, before Voss disappeared, that there was an active discontinuity at that address.

  Crowe looked at the sketch.

  He who finds it, is found.

  But what about someone who already knew where the gaps were? Someone who had mapped the city not by the cases they left behind — but by the intervals themselves?

  He filed the question with the care it deserved. There was no folder for it yet.

  But there would need to be one soon.