AI Quinn counted the footprints twice and got the same wrong answer both times.
Hundreds of them pressed into the dust on the old platform, and every single one pointed the same way. Towards the tunnel mouth. Not one came back.
"Ravers," said Rennick. He stood under the dead lamp with his hands in his coat pockets, rocking on his heels, the way he did when he wanted to be somewhere with a kettle. "Camden's full of them. They break the padlock at the vent shaft, they bring cans and a Bluetooth speaker, someone's had a bad pill and the rest scarper."
"Scarper where?"
"Out."
"Show me one print heading out."
He looked down. Rocked twice more. "They'd walk in their own tracks, wouldn't they. Coming back."
"Two hundred people walking home single file in the dark, all placing their feet in the same holes." Quinn crouched at the edge of the cordon tape and let her torch skim the dust at an angle, low, so the ridges threw shadows. Trainers. Boots. Bare feet, two sets, small. One long smooth drag like a hem sweeping. "Try again."
The station had no name on any Tube map printed since 1924. The tiles were the colour of weak tea where they weren't black with a century of brake dust, and the arch above the platform curved down into that particular underground silence which is not silence at all, but a low hum in the sinuses . Cabling hung in loops. Sandbags rotted against the wall from a war two generations dead. Somebody had leaned a stack of fruit crates near the WAY OUT sign, and the crates were new. Quinn had noticed that first, before the body, and she hated that she had noticed it first.
Copper stung her nostrils. Blood, and under the blood a sweetness, like fruit going over in a warm room.
The dead man lay eleven feet from the platform edge, curled on his side with his knees drawn up and both palms turned to the ceiling. Male, mid-forties, grey at the temples, a good wool overcoat gone shiny at the elbows.
"Fell down the shaft," Rennick said. "Sixty-foot drop, lands, crawls, gives up."
"Then where's his blood?"
"He's lying in it."
"He's lying beside it." Quinn moved her torch left . The stain sat in the dust as a neat dark disc, eighteen inches across, with a clean lip around the outside as though someone had drawn round a dinner plate. Nothing had splashed. Nothing had run. Blood ran. Blood always ran, downhill, into cracks, into the crown of your shoe if you stood in the wrong place, and this platform sloped a good inch towards the track. "Blood goes where gravity tells it. This sat still and waited."
Rennick's chin came up. "Someone tidied."
"With what? There's no smear. There's no cloth, no bleach, no water. Look at his soles."
He didn't want to. He came anyway, ducking under the tape, breathing through his mouth. Quinn tilted the torch onto the dead man's shoes. Brogues, resoled twice, the leather worn pale at the ball of the foot.
Clean. Not spotless like a shop shoe, but clean the way shoes are clean when a man has walked on carpet and pavement and stairs, and then not walked at all. No dust rimming the welt. No grit in the tread. Sixty feet of Victorian brick dust hung in the air of this place, and the man lying in it had none on him below the ankle.
"He never walked in," she said.
"So he was carried."
"Yes. And put down gently , and by someone who cared how he looked." She followed the line of the man's spine with her light. "See his coat? Buttons all done up, top to bottom. Hem straight. Nobody who's been dropped down a ventilation shaft lands with his coat buttoned and his collar flat. And his knees."
Mud. Dried, pale, the colour of clay, crusted across both knees of his trousers and nowhere else.
"He knelt in wet ground," Quinn said. "Then he was moved here, and there's no wet ground within a mile of us."
Rennick laughed, a short unhappy sound that bounced off the tiles and came back at them from the tunnel. "You want me to write that in the log, boss? Dead man kneels somewhere else, gets flown in?"
"I want you to write what you see and stop deciding what happened before you've looked at it."
She circled the body, counting her paces, keeping to the plates the SOCOs had laid. Eleven feet from the edge. Twelve feet from the wall. And around him, in a ring perhaps thirty feet across, the platform floor was swept . Not clean, swept. Dust pushed outwards from the centre in fine radiating lines, like frost on a window, like something had breathed hard and flat across the ground once and stopped.
Every footprint on the platform stopped at the edge of that ring. Not one crossed it. Two hundred pairs of feet had walked to the boundary, turned, and gone along it.
Quinn crouched again and put her nose an inch from the floor. The sweetness came stronger there. Beeswax. Salt. Something floral and rotten underneath, orchids left in a vase too long.
"Rennick. When did the call come in?"
"Anonymous. Eleven forty. Male voice, said there was a body at the old platform and gave the shaft access, gate code and all."
"There is no gate code. That gate's been padlocked since British Rail owned the tunnels."
A pause. "There's a keypad on it now."
"Installed by whom?"
Another pause, longer. "I'll find out."
She lifted the dead man's chin with two gloved fingers. His jaw came up stiff, then gave, and his lips parted, and something clicked against his teeth.
A disc of bone, yellowed, the size of a ten pence piece, sat under his tongue. A shape cut into one face: three curved lines meeting like the spokes of a broken wheel.
Quinn had seen that shape before. She had seen it burnt into the wooden windowsill of a flat in Bethnal Green three years ago, with her partner's coat over the back of a chair and DS Morris nowhere in the world at all, then or since.
Her hands stayed steady. She had spent eighteen years making sure her hands stayed steady.
"Bag that separately," she said. "Not with the clothing. Separately, and I want it in my hand before it goes anywhere near a lab."
"That's not-"
"Separately."
She went through the coat next. Pockets sewn shut, all four of them, with black thread and neat little stitches, the work of someone patient. Inside the left breast pocket, which somebody had unpicked and then resewn badly, her fingers found metal.
A compass. Small, brass, the casing furred green with verdigris, the face crowded with tiny etched marks that were not points of any compass she'd been taught . The needle swung as she lifted it, settled, and pointed straight past her shoulder into the tunnel mouth.
Quinn turned. The needle turned with her, holding its line, patient as a dog.
"That's north," Rennick said. "Roughly. Isn't it."
"North is behind you."
The lamp above them, the dead one, the one that had no bulb in it, came on. Filament light, warm and yellow, throwing both their shadows down the platform and into the ring of swept dust, where they lay too long and too thin.
Rennick's radio hissed. A constable's voice arrived thin and fast, tripping over itself.
"Guv, we've detained a female at the vent shaft, she's got a satchel full of books and she's saying she needs to speak to Detective Quinn, she says by name, and, guv, there's something coming up the stairwell behind her."
The needle in Quinn's palm began to spin.