A professor murdered in his own locked laboratory. A frightened man who fits the crime a little too neatly. And a quiet, reasonable hand steering the case away from the truth.
On a wet Saturday night in October, Professor Robert Arnold is found dead in his Glasgow laboratory - bludgeoned and hidden inside a freezer. No one can explain why he was there after dark, alone, in a sealed room he had no business entering.
To the Specialist Crime Squad, the answer looks straightforward. A troubled man with a grievance. Poison-pen letters. An obvious suspect.
But Detective Sergeant Don Maciver - newly transferred from Oban, with a son in a hospital bed and a marriage under strain - can't make a frightened letter-writer fit the cold, careful thing that was done to Arnold.
The harder Maciver pulls at the case, the more he feels a hand on it that isn't his: easing the investigation away from the truth and toward a man who didn't do it.
Because what Arnold was building in that sealed room is worth a fortune to people who never raise their voices, never leave a mark, and never need to do anything monstrous themselves.
To get near the truth, Maciver will have to see past the answer everyone wants - and decide what he is willing to lose for a man already halfway to prison for a murder he didn't commit.
For readers of Ian Rankin, Val McDermid and Denise Mina.
He had left the lights off on purpose, and the dark made the work feel exactly as illicit as it was.
The fifth-floor windows, lit up, would throw out across the dead campus like a lighthouse - a lab burning on a Saturday night, a question someone might come and ask. So he worked by what leaked in: the corridor strip through the doorway, and the hard yellow of the flow hood, and the yellow made the wire of white at his temples look like something dug up. October rain came and went against the glass. Fourteen floors of the Frost Building across the courtyard were dark. One was not.
He was not supposed to be at a bench at all. Not anymore. He had not held a pipette in a decade before this spring. The first night back, standing alone in the dark, the skill returned before his head had caught up. Forty years of muscle memory, intact. He'd been surprised to find it still there, and then surprised to find himself weeping.
He thought about Mary. He always did, here, with the work under his hands and nothing to stop his mind going where it went.
He did not hear the figure that had been standing in the doorway for the last three minutes.
It had come in while the door stood open, while the sound had been his own. It had stood in the dark and watched him and considered its moment. The swinging door had been an error. It had nearly sent them home.
It did not send them home.
Euan was in the bed with the television on and the sound off, watching it the way he watched everything now, from a great and deliberate distance.
"There's a boy on the ward," Euan said. A long time later. "Came in last week. Younger than me. Diving."
"He keeps asking the physios when he'll be back to normal. They'll not tell him. Just - we'll see how you get on. And he keeps asking."
"I wanted to tell him to stop asking," Euan said. "It's easier when you stop asking."
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