AI The Saint Christopher medallion gave him away. It caught the light of a chip shop window as he turned, a small silver flash at his throat, and Quinn was moving before her brain finished the sentence.
"Herrera!"
He ran.
Of course he ran. Eighteen years on the job had taught her that innocent men freeze, guilty men explain, and the ones who bolt are the ones who know something worth the sprint. Tomás Herrera knew something. He'd known it since she'd found his fingerprints on a bag of surgical clamps in a flat where a man had bled out on a mattress and then, according to three separate witnesses, walked away.
Rain came off the awnings in sheets. Camden High Street at half eleven, and the pavement was still busy with the ragged end of a Saturday, students in wet denim, a man selling umbrellas that turned inside out the second you bought them. Herrera went through them like water through a grate. He knew the ground. She could see it in the way he cut left before the corner even arrived.
Quinn's radio pressed cold against her collarbone. She thumbed it.
"Foot pursuit, Camden High Street heading north, male IC3, dark jacket, five ten. This is DI Quinn."
The reply crackled back, thin and unhelpful. Units eight minutes out. Eight minutes. He'd be in Scotland.
She ran.
Her knee complained on the third stride, the way it always did now, a hot wire under the cap where a stolen Vauxhall had introduced itself to her in 2011. She ignored it. Her breath came in the old rhythm, in through the nose, four steps, out through the mouth, four steps. Military precision, her sergeant used to call it, back when she was twenty-two and could do this all night.
Herrera glanced back at the lights.
Mistake. Everyone looked back. It cost him half a second and she took it, closing to twenty metres before he hit the bridge over the lock.
"Police! Stop running and we can talk!"
"You don't want to talk!" His voice came ragged over his shoulder, that soft Andalusian slant on the consonants. "You want a file with my name on it!"
"I want the man who died in Peckham!"
"He didn't die!"
He vaulted the barrier by the canal steps and dropped out of sight.
Quinn hit the barrier a breath later, threw a leg over, and went down the steps two at a time. Wet iron. Her hand skidded on the rail and she felt the cold ribbon of pain where the rust opened her palm. The canal came up at her, black and pitted with rain, the water carrying broken neon in long smears. Someone had left a bicycle wheel chained to nothing.
He was already forty metres along the towpath, and he was fast, and he was twelve years younger than her.
She hated that. She hated it so much she found another gear.
Under the bridge the sound changed. Their footfalls came back doubled, tripled, the drip of the arch loud as a metronome. It smelled of diesel and wet stone and, faintly, of something sweeter, like burnt sugar left in a pan. She'd noticed that smell twice before. Once in an evidence locker. Once in the flat where Morris had gone in ahead of her and come out wrong.
Three years, and she still couldn't put a name to it.
Herrera cut right, up a ramp, through a gap in the hoardings behind the market. A builder's sign flapped there, TEMPORARY WORKS, and behind it a stairwell descended into a hole in the earth that no council had ever advertised.
Quinn stopped.
Rain ran off her nose. Her lungs burned. Down there, past the reach of the streetlight, a strip of green light bled up the tiles. Not the sodium orange of a service tunnel. Green, and low, and moving, like something breathing at the bottom of a well.
Her radio hissed. She looked at it. Two bars, then one, then nothing.
*Right.*
She should wait. That was the answer any inspector with a pension worth protecting would give. Wait, call it in, get a search team, get lights, get a map of the disused Camden line that half the surveyors swore had been backfilled in 1926.
She thought about Morris. About standing in a corridor exactly like this one, waiting for the right thing, and the way his shoes had looked afterwards, side by side, laces still tied, and nobody in them.
Quinn went down the stairs.
Forty steps. She counted them because counting kept her breathing even. The tiles were cream and rot-brown, and someone had scratched shapes into the grout, small looping marks that hurt to look at directly. The temperature dropped. Not damp cold. Dry cold, like a freezer door left open, and the burnt-sugar smell got thicker until she could taste it at the back of her throat.
Then the sound arrived, and it stopped her dead with one hand on the wall.
Voices. Hundreds of them. The bright churning hum of a market in full swing, bartering and laughing and somewhere a fiddle sawing a tune she almost recognised. Under Camden. Under the ground she'd policed for eighteen years.
At the bottom of the stairs stood a man built like a door, arms folded, wearing a bus conductor's coat about ninety years out of date.
"Token," he said.
"Detective Inspector Quinn, Metropolitan Police." She had the warrant card out. "A man came through here in the last minute. Dark jacket. I need to know where he went."
The doorman looked at the card. He looked at it the way you look at a child's drawing.
"Token," he said again.
"I'm not asking."
"Then you're not entering." His breath came out grey. "Bone, palm-sized, marked. No token, no market. That's not my rule. I just stand here."
Behind him, past the arch, the light moved. Green and gold, lantern light on a hundred faces, stalls crowding the length of a platform that had no train and no timetable. Someone was selling something in a jar that pressed itself against the glass.
Quinn's mouth went dry.
Two metres to her left, a young man in a puffer jacket was fumbling with his phone, one hand digging in his pocket, and a pale disc came out with his keys and hit the tiles with a click.
She had it before he'd finished swearing.
"Oi, that's mine!"
"Crown property now." She held it up. Bone, yellowed, warm as a coin out of a fist, cut with the same looping marks as the grout. The moment her thumb crossed the marks they shifted under her skin like something turning over in sleep.
The doorman stepped aside.
"On your own head," he said.
The arch let her through and the market swallowed the sound of the rain entirely. Quinn came out onto the platform and it was wrong in a way her body understood before her mind did, the ceiling too high, the tunnel mouth at the far end curtained in hanging chains, a tiled sign on the wall reading a station name that had never existed. Smoke hung in flat layers. A woman with too many rings was weighing teeth on brass scales. A butcher's stall displayed cuts she couldn't identify from animals she wouldn't name.
And thirty metres down, Herrera stood with his back to her, talking fast to a figure in a grey coat, gesturing at his own throat where the medallion sat.
Quinn started walking.
The market noticed her. It happened the way a field of birds notices a cat, a ripple, a hush spreading outward, stall by stall, until the fiddle stopped mid-bar. Every face turned. Hundreds of them. The jar stopped moving.
Herrera spun round, and his eyes went wide, and he shouted something at her that she never heard.
Because behind him, the figure in the grey coat straightened up. Turned. Smiled.
"Harlow," it said, in DS Morris's voice. "You took your bloody time."