Crowe went to Drest the following morning.

  He hadn't given notice. He never did — announced visits allowed time for preparation, and preparation was the enemy of genuine reaction. What a person did in the first five seconds upon seeing an unexpected face at the door said more than any prepared answer to any prepared question.

  Drest opened the door and in the first five seconds showed genuine surprise, followed by something Crowe catalogued as caution — not guilt, not fear, caution. The difference was important and he registered it without developing it yet.

  — Crowe — said Drest. — Come in.

  The room was the same as the last visit. The worn armchair, the clean desk with the open notebook, the few books in a straight line. The tea this time was fresh — Drest had woken recently, or had just made it without specific reason, or had been warned somehow by a means Crowe had not yet identified.

  He registered all three possibilities without discarding any of them.

  — I have new information about the case — said Crowe, sitting without being invited as was his habit. — And some questions that follow from it.

  Drest sat in the worn armchair. He folded his hands over the closed notebook — the same gesture as last time, which meant it was habit and not performance.

  — Ask — he said.

  — The Londrivar Academy of Applied Sciences — said Crowe. — You had a connection to the department of experimental neurology.

  It was not a question. Drest didn't answer it as though it were.

  — I did — he said. — Informal collaboration. Adjacent areas of interest. — A pause. — It ended along with the rest of the institution.

  — The department's pharmacological research programme developed an alkaloid-based compound with effects on short-term memory — said Crowe. — That compound is being synthesised in an improvised laboratory in a factory in the Industrial District. Workers exposed to it lose memory of specific shifts. The phantom shifts cover nocturnal use of the factory.

  Drest was quiet.

  Crowe observed. There was something in the silence that was not what he had expected — not the reaction of someone who had been caught, not guilty recognition, not even complete surprise. It was the silence of someone processing new information within a context that already existed.

  — You think I'm involved — said Drest.

  — I'm establishing whether you are — said Crowe. The distinction was genuine. — The compound comes from the Academy. You have a connection to the Academy and to the research on the interval. The overlap is sufficient to justify the question.

  Drest stood. He went to the window — the same movement as Maren in the Guard's offices, which Crowe had learned to recognise as the gesture of someone who needs physical distance to organise what they are about to say.

  — I am not involved in the factory — he said, with his back turned. — I don't know who is using the compound or for what. — He turned. — But I know whose formula it is.

  Crowe was quiet.

  — There was a researcher in the neurology department — said Drest, returning to the armchair but not sitting, standing behind it with his hands on the back. — Young, brilliant, with a specific interest the rest of the department considered eccentric. He was developing compounds that affected perception and memory — not for medical application. For field application. He wanted to create conditions in which a subject could experience what he called a liminal state — a state between normal perception and expanded perception.

  — Related to the interval — said Crowe.

  — He believed the interval was not only a physical phenomenon — said Drest. — He believed there was a perceptive component. That certain people, in certain states, could perceive it naturally. And that it was possible to induce that state artificially.

  Crowe was completely still.

  Thomas Reed. Twelve twenty at night. The almanac. And then nothing — until the factory, with damp earth on his knees that was not from the factory floor.

  The theory he had built the previous evening was intact. But there was something in this new information that did not fit the way it should, and he could not yet identify where the gap was.

  — The name of this researcher — said Crowe.

  — Harlan Vex — said Drest. — He was dismissed from the Academy two years before its closure. Misconduct in research — experiments without the subjects' consent. — He paused. — I never knew where he went after.

  Harlan Vex. Crowe added the name to his mental list with the note that he needed an address, a history, any record the Guard could find.

  But there was something more pressing.

  — The liminal state — said Crowe. — If someone were exposed to the compound involuntarily. Without preparation, without context, at an uncontrolled dosage. What would happen.

  Drest looked at him with the expression of someone realising the conversation had arrived at a point he hadn't anticipated.

  — It would depend on the individual — he said, slowly. — On natural perceptive sensitivity, on the mental state at the moment of exposure. — He paused. — In most people, only the memory loss. But in some — in people with specific sensitivity to this kind of perception — there could be something more.

  The narrative has been illicitly obtained; should you discover it on Amazon, report the violation.

  — What exactly.

  — Involuntary experience of the liminal state — said Drest. — Fragmented perception of things that would not normally be perceived. — He looked at Crowe with an attention that had shifted in quality. — Such as finding oneself somewhere without knowing how one got there.

  The room was silent.

  Thomas Reed. Damp earth on his knees. A place that was not the factory and not his home.

  Crowe stood.

  — I'll need everything you have on Vex — he said. — Any correspondence, any documents from the Academy period.

  — I have little — said Drest. — But what I have is yours.

  Crowe went to the door. Stopped.

  There was a question that had arrived while Drest was speaking and that he had not yet asked because he wasn't sure how he would receive the answer. But he needed the answer more than he needed the comfort of not asking the question.

  — Voss — he said. — When he came here three weeks ago. Did he ask about Vex's compound?

  Drest was quiet for a moment that was too long to be simple.

  — No — he said. — But he asked whether it was possible that someone was trying to force access to the interval artificially.

  — And you replied.

  — I said it was theoretically possible — said Drest. In the voice of someone delivering a weight they had carried alone. — And that the consequences of doing so without fully understanding what the interval was would be unpredictable.

  — Voss seemed concerned by that.

  — No — said Drest. And there was something in the word — a specific texture that took Crowe a moment to identify. — He seemed relieved. As though confirmation that it was possible was precisely what he had come to find.

  Crowe stood in the doorway for a moment with that.

  Then he left.

  On the way to the Guard, with Pell's notes in one pocket and the name Harlan Vex in the other, Crowe built the complete theory for the second time.

  Vex — dismissed from the Academy for experiments without consent — had continued the work independently. Had set up the improvised laboratory in the factory. Was producing the compound to create conditions for artificial access to the interval. The exposed workers were a side effect — not the objective. The objective was something else. Someone specific.

  And Voss had known this. Had gone to Drest to confirm it was possible. Had been relieved — not concerned, relieved — which meant the confirmation served some purpose he already had.

  The instrument he had calibrated for Mourne. The final calibration stage on the night of the disappearance.

  There was a connection. There had to be.

  The theory was coherent. It was elegant. Each piece fitted the next.

  Crowe walked with his hands in his pockets and the headache growing behind his left eye, and he did not notice — not yet — that he was building the same structure he had criticised in previous cases: a narrative that explained everything, leaving no room for what didn't fit.

  The earth on Reed's knees didn't fit.

  Drest's expression when he had said relieved didn't fit entirely.

  And there was a question he had not asked — small, almost irrelevant, the kind he normally asked automatically and which this time he had simply not asked.

  He had not asked Drest where Voss had gone after leaving the office on that afternoon three weeks ago.

  He had not asked because he already knew the answer. Because the theory said he knew.

  And that certainty — that feeling of knowing before verifying — was exactly the kind of thing Crowe had spent years learning not to do.

  But the theory was so good.

  Maren was waiting at the Guard with a list in hand and the expression of someone who had news and was calculating how to present it.

  — Harlan Vex — said Crowe, before Maren could open his mouth.

  Maren blinked.

  — How do you know that name — he said.

  — Drest. Researcher dismissed from the Academy, specialised in compounds with perceptive effects. I need an address and a history.

  Maren looked at the list in his hand. Then at Crowe.

  — Vex is on the Harwick staff list — he said, with the voice of someone delivering a confirmation they hadn't expected to be quite so direct. — Hired eighteen months ago as an equipment maintenance technician. — A pause. — Under a different name. But the physical description Harwick's manager provided matches the Academy record.

  Crowe was completely still for a second.

  Then he felt — didn't hear, felt — the pieces clicking into place with that particular mechanical satisfaction that was the best and worst thing about the way his mind worked. The best because it was almost always a sign he had arrived somewhere real. The worst because sometimes the fit was illusory — the mind completing the pattern because it wanted it to be complete, not because it was.

  — Residential address — said Crowe.

  — A lodging house in Lower Londrivar — said Maren, consulting the list. — Old Iron Street, number thirty-one. — He paused. — Crowe.

  — Yes.

  — The guard who did the rounds on the night you were in the factory — said Maren, in the tone of someone being careful about the sequence. — He submitted a report this morning. He said that during the rounds he felt sudden nausea and lost approximately twenty minutes of memory.

  Crowe looked at him.

  — The rounds were earlier than scheduled — said Crowe.

  — They were — Maren confirmed. — The guard left early because he was having trouble sleeping. — A pause. — He said his last memory was being in the external yard. He came to inside the factory, in the central corridor, without knowing how he had got in.

  The central corridor.

  Where Crowe had been hiding between the hydraulic presses.

  He was quiet for a moment with that information — not with what it meant for the guard, but with what it meant for the space. The compound had been active that night. It had been in the air while he himself was inside the factory.

  — How long were you in there — said Maren. In a voice that had ceased to be professional and had become something else — more direct, more personal.

  — A little over two hours — said Crowe.

  — And.

  — I'm fine — said Crowe.

  Maren looked at him for a moment with those small brown eyes that observed with the calm that people mistook for slowness.

  — Are you certain — he said.

  Crowe thought about the headache that had woken with him that morning. About the moment on Alchemists' Street when he had lost the thread of a thought for three seconds and then recovered it without knowing where it had gone. About the steam that had seemed to descend rather than rise on that street, days ago.

  — Yes — he said.

  Maren did not look entirely convinced. But he didn't press — it was the kind of respect that existed between them, the mutual recognition that there were questions that would not be answered and that insisting did not make them answerable.

  — I'm going to Vex's address — said Crowe.

  — I'll send two guards.

  — No.

  — Crowe —

  — If we arrive with guards he'll be gone before we reach the second floor — said Crowe. — Let me go first. If there's anything the Guard needs to deal with, you'll have the address.

  Maren was quiet for a moment with the list in his hand.

  — Tomorrow morning — he said. — If I haven't heard from you by nine, I go with the guards regardless.

  — Reasonable — said Crowe.

  He left with the lodging house address and the complete, coherent theory in his head, and with something else he had not admitted to Maren — a three-second gap one morning that he had attributed to tiredness, and the persistent feeling, since the factory, that something was slightly different about the way environments presented themselves to him.

  As though the edges of things were one degree less defined than they ought to be.

  He attributed that to tiredness too.

  It was easier that way.