AI The stairwell smelled of iron and cold stone, and Quinn counted the steps down out of habit. Forty-two. Camden Town's disused southbound platform sat sixty feet under the pavement, sealed since 1924, and the fire door at the bottom had been cut open with an angle grinder sometime in the last twelve hours. The burrs on the metal still had a shine.
"Mind the rail, ma'am." DC Femi Adeyemi held the door with his shoulder, torch tucked under his arm. "Uniform's got a chain of custody sorted but the place is a nightmare. No lighting. Generator's on its way."
"Who found him?"
"Urban explorer. Twenty-two-year-old with a GoPro and a hobby. He's upstairs being sick into a evidence bag, which I've asked him three times not to do."
Quinn stepped through onto the platform and stopped.
Her torch beam swept tile the colour of old teeth, the pale ghost of a Nestlé advert from another century, and dust. That was the first thing. The dust lay in a skin across the platform, an even grey felt that had been settling for a hundred years, and it was wrong. Not the dust itself. The pattern in it.
"Body's down here," Femi said, moving off .
"Wait."
He waited. Quinn crouched, elbows on her knees, and angled the light low across the floor so the beam skimmed it. Shadows raked out long. In the dust, running the length of the platform, lay two parallel lines of small rectangular voids — clean spots, sharp-edged, each about the size of a paperback. They marched in rows. Dozens of them. Between the rows, the dust had been scuffed into a broad path by feet. Many feet.
"Tables," she said.
"Sorry?"
"Trestle legs. Two rows, facing each other, with an aisle between." She stood, and her knees complained about it. "Somebody had a car boot sale down here."
Femi laughed, then stopped laughing when she didn't. "Squatters? Rave? We get raves in the deep stations. Kids run cables off the maintenance supply."
"A rave leaves cans. Nitrous canisters. Fag ends." She turned a slow circle . "Look at the floor and tell me what you see."
He looked. "Nothing."
"Nothing," she agreed. "Somebody swept up. Somebody who set out ninety-odd tables in a sealed tunnel and then went round afterwards collecting their rubbish."
The body lay eighteen metres along, at the mouth of a cross-passage, and the first uniform on scene had done the sensible thing and stood well back with a clipboard. Quinn snapped fresh gloves and crouched. Male, fifties, thin, dressed in a wool coat that had cost money in about 1988. Face down, left cheek against the tile, arms drawn up under him.
"So," Femi said, and she heard him settle into it, the way young detectives did when they'd already written the report in their head. "Working theory. He's part of it — the market, whatever it is. Deal goes wrong. Someone puts a blade in him, everyone scatters, they clear the stalls to strip the scene. That's why it's swept. It's not tidiness, it's cleaning."
"Where's the blade wound?"
"Under him, I'd guess. There's a lot of blood."
Quinn moved her torch. There was a lot of blood. It had spread from beneath the body in a broad, dark lake, and the edges had dried to a lacquer, and that was the second thing that was wrong.
"Femi. Come here. Get down."
He got down.
"Which way does the platform slope?"
He hesitated. "Towards the tunnel mouth. There's a drainage fall, they all have it."
"So." She traced the air an inch above the surface. "He's lying on the high side. Blood runs downhill. Water does, wine does, blood does. This ran uphill." Her finger followed the lake to its far margin, where the dark tongue reached three feet up the slope and stopped in a crescent, as if it had lapped against something and been turned back. "And then it stopped. Not soaked in, not spread thin. Stopped. There's a line."
Femi put his torch beam on it. The crescent held. Beyond it, clean tile.
"Surface tension ," he tried.
"On unglazed hundred-year-old tile with a groove in it every four inches." She stood and walked the crescent, following it out from the body in a curve. It kept curving. It closed on itself. A circle, near enough seven feet across, with the dead man inside it, and the blood pushed up against the inner edge all the way round like a tide against a harbour wall.
"That's—" Femi said, and stopped.
"Say it."
"That's a containment. That's a circle. Cult stuff. Chalk, salt, whatever, and they've lifted it after, and the blood's set into the—" He was talking faster . "There'd be residue. Ma'am, there'd be residue, we can swab the line—"
"Swab it." She was already moving . "And Femi. Look at his shoes."
The dead man's shoes were brown brogues, resoled, laced tight. The uppers were clean. The soles were clean. Femi crouched, tipped his head, and she watched him get there.
"There's no dust on him."
"Forty-two steps and eighteen metres of century-old filth," Quinn said. "I've got a tidemark on my trousers to the knee. Yours are worse. His are pressed."
"So he was carried."
"By whom? Show me the drag marks. Show me two sets of prints coming in heavy and going out light." She swung the torch back across the floor around the body. The scuffed path of feet ran up the aisle and past — and stopped, ten feet short, as if the crowd had flowed around the circle without ever crossing it. Inside the circle the dust was undisturbed except where the blood had gone. No prints. Not one. Not even his.
Femi was quiet for a while. The generator coughed somewhere far above, failed, coughed again.
"Ma'am, there's a version of this where I don't have to write down what I'm looking at."
"Give me it."
"He came down here on his own. Something in his coat, drugs, whatever, seized him, he went over, he bled, and the airflow off the tunnel — there's a draught, feel it — the airflow dried the blood in a pattern that reads like a circle because we're standing here at four in the morning wanting it to read like something. The stalls are a rave. The urban explorer contaminated the floor. And I put it to the coroner as unexplained and go home." He rubbed his face . "That version's got a lot going for it."
"It's got everything going for it except the floor." Quinn took her torch off the body and put it on the tile just outside the circle's northern arc, where a delicate white bloom spread across the ceramic in feathers and needles. She held her bare palm above it. The air bit.
"That's frost," Femi said.
"It's the eleventh of June."
Something clicked under the man's chest when she eased his shoulder, and she stopped, and photographed, and eased again. His right hand had closed hard in death around two objects. The first was a flat disc of yellowed bone, drilled once at the edge, worn smooth as a tumbled pebble.
The second was a brass compass, small enough to hide in a fist, its casing furred green with verdigris, its face cut all over with marks that were not letters and not numbers.
The needle was turning . Slowly, steadily, without stopping, like a thing looking for something it couldn't find.
Quinn held very still and watched it go round, and round, and round, and thought about a night three years ago on a canal towpath in Hackney, and about DS Morris, and about the eleven minutes of her life she had never been able to account for.
"Femi."
"Yeah."
"Don't log that."