The woman standing at Nadia's fume hood was running one finger along the sash as though checking a shelf for dust.

"It's clean," said Pilar Obuya-Dunmore, without turning round. "I'll say that for you. Most chemists I've met leave a lab like a teenager leaves a bedroom."

Pilar was fifty, built like a door, and had worked for Imelda Reyes-Whitlock for twenty-two years in a role no one had ever managed to name. She collected rents. She delivered bad news. She was a wolf, and she stood in the lab with her nostrils lightly flared and her eyes on the extraction hood, and Nadia understood from the way her shoulders sat that she was trying very hard not to look at the person the room was missing.

Toby was sitting on the rolling stool by the balance, hugging a box of pipette tips like a hostage.

"I didn't say anything," he said. "I want that on record. I said, 'We are a small business offering cleaning products,' and she said, 'Of course you are, love,' and then she looked at the GC-MS."

"It's a very good GC-MS," said Pilar. "Nobody buys one of those to clean carpets."

"Imelda owns the building," Nadia said. "She's known what I do since the day I signed the lease."

"Imelda knows a woman upstairs makes something. That's different from knowing a woman upstairs is being followed up Cutbank Lane by a Registry auditor in a suit that cost more than your rent." Pilar finally turned. She had a heavy, tired face, and she looked at Nadia the way people look at a staircase in the dark. "He's still out there. Under the laundromat sign. Pretending to read a bus timetable. The bus doesn't come down here."

Nadia did not look at the window. It took some effort.

"He's following me for a conversation," she said. "I'm handling it."

"Imelda would like you to handle it at dinner."

"Tonight?"

"Seven. Her kitchen. She says bring bread, since you never bring wine." Pilar's mouth did something that was nearly a smile. "She also says that when a wolf from the Strata walks down her street in good shoes, she wants to know why, and she'd rather hear it from you than from forty people at the market."

"Tell her I'll be there."

"Tell her yourself. I'm a rent collector, mija, not a pigeon." Pilar picked up her coat from the back of Toby's stool, paused beside Nadia, and lowered her voice. "I can't read you. I never could. I always thought it was the soap, but I've been in a lot of laundromats. It's none of my business what it is. But if that boy downstairs can't read you either, he'll start to wonder, and then he'll start to look. Be careful."

She went out. Her boots took the stairs one at a time, heavy, unhurried, like someone who had never needed to run from anything.

Toby waited three full seconds.

"Okay," he said. "What did you do."

"I'll tell you what I did," Nadia said. "I took a job from a man who wasn't a wolf, in a room where everyone else was. And I've been an idiot. A Registry auditor says my signature is in his bond."

"Your *signature*?"

"The little extra thing in the note. The tidy part."

"The thing you said was impossible to detect?"

"That."

Toby slid off the stool and went entirely white, a colour he had been practising since he was eleven. "Is he going to arrest us? Because I want to flag I haven't done my taxes since March, and I think that's separate, but a clever prosecutor could bundle them."

"He's not arresting anyone. He gave me this."

She laid the sealed case on the bench. Toby stared at the Registry stamp as though it had a face.

"That's his bond swab," he said, very quietly. "From the actual archive. That's, like, a crime. That's *the* crime. We're holding the crime."

"Gloves on."

Her hands knew the work better than she did. Snap of nitrile; scalpel through the seal; a glass slide, a dab of solvent, a flick of the pipette into the autosampler vial. Toby fussed at the GC-MS, which rattled awake with the noise of an old fridge being murdered. Nadia hit run. They had forty minutes to wait, and nothing in the world to do with them.

She went to the window.

Down on the lane, in the orange wash of the laundromat sign, Kaveh Dastgheib stood exactly where Pilar had said, one shoulder against the bus shelter, studying a timetable for a route that had been cancelled in 2019. He had loosened his tie. A woman went by with a bag of washing and said something to him; he bowed his head politely, and she laughed in alarm and sped up.

"He's very polite," Toby observed, at her elbow. "For a man who wants to ruin us."

"He doesn't want to ruin us."

"He wants *something*."

"He wants to know if his life is real," she said, and then wished she hadn't, because it made her aware that she had been thinking it since the lift.

They didn't talk after that. Toby fiddled with his phone and put it away. At some point he made two cups of tea in lab beakers, which was against every rule she had, and she took hers.

The machine chimed.

Nadia was back at the screen before the sound had finished. The chromatogram came up in its usual stupid, beautiful pattern of peaks: the little hills of Braid's base compound, which she could have drawn from memory, and the shared-note analogue riding on top, tidy as a hymn.

"That's mine," she said. "It's mine. Look. Same retention time, same profile."

"Oh no," said Toby.

"But the date's wrong. This is three years old. It's cold-stored. I wasn't even..." She stopped.

Behind the second peak, a hair's width to the right, there was a small shoulder she hadn't expected. A compound her formula didn't contain. Her fingers were already at the keyboard, pulling the mass spectrum, overlaying it with her library.

No match.

She pulled the older library. The one she had built at university, the one she'd never wanted to open again.

No match.

She pulled the last one, which wasn't a library at all but a folder of scans with a name she hadn't read in four years, *P. Quispe, notebooks, vol 1–9*, and her own breath went somewhere she couldn't follow it.

"Nads?"

"It's a by-product," she said, hearing her voice go technical and calm, the sure sign that she was frightened. "A synthesis impurity. When you make the base compound by a specific route, a certain contaminant builds up. It's there at about two percent. You can't remove it without losing yield. I don't use that route. I use a cleaner one that I developed myself, and it doesn't leave that peak."

"So whose route is it?"

On the screen the little shoulder sat beside the hill like a thumbprint on glass.

"My father's," said Nadia.

Toby didn't say anything. For once in his life, he didn't say anything at all.

She sat down on the stool. In the window behind her, Kaveh Dastgheib turned over a bus timetable and read the other side. Somewhere in the walls the building shuddered as the washing machines below began their evening cycle, a deep wet rumble she'd slept through for two years.

Her father had died of a stroke on the floor of his own clinic. That was what she had been told. He had been a gentle, absent, brilliant man who smelled of nothing, as she did, and who had never explained why. She had thought the nothing was a small family curse.

She had not thought it was a method.

"Somebody made that bond," she said, "using Dad's recipe. Three years ago. Before I'd even started."

"Okay," said Toby, in a very small voice. "And who is the somebody?"

Nadia looked at the window.

She did not know. She took off her gloves, binned them, and went downstairs with the dregs of her tea still in her hand, because she needed her face to be doing something other than thinking.

The night had come down in the canyon the way it always did, from the top, the Rim lighting up first like a row of struck matches. Kaveh straightened off the bus shelter when the laundromat door opened. He looked at the beaker in her hand.

"Is that tea?"

"It's the only glassware I trust," she said. "The swab is genuine. Your file is genuine. Part of it is mine."

"Part."

"Part. I can't say more tonight. I have a dinner with a landlady who'll skin me if I'm late, and I need to look at something that isn't a screen." She held his eye. "Give me till tomorrow."

He weighed it. He was a man who, she was starting to see, weighed everything, including whether to breathe.

"Noon," he said. "At the Registry, in my office, and you'll sign in as Nell Owens, because it is a very good piece of paper."

"Is that a joke?"

"I'm told I have one every fortnight." He stepped back onto the kerb. "Thank you for the tea, Dr. Quispe-Halloran. I didn't get any."

"It wasn't for you."

"I know," said Kaveh. "That is why it was kind."

He walked away up Cutbank Lane, and she stood in the neon with the empty beaker, thinking that she had come down to lie to him and had told him, instead, the truth, and she did not know when that had stopped being a mistake. Somebody, years ago, had used her father's recipe to build the thing she was now selling. She knew only that a man in a charcoal suit was walking away with a broken life, and that she was about to be the only person in Tessarine who could tell him what had broken it.