Stephanopoulis and I went in behind them, which counts as first if you’re not the entry team in case you were wondering, wearing our stab vests under our jackets and extendable batons on our belts. Beyond the door was a windowless hallway with a closed internal door on the left and a double stairway going down on the right. When I tried the switch we were rewarded with a dim light from an unshaded forty-watt bulb. Ancient flocked wallpaper in gold and red covered the walls, peeling where it met the ceiling.

Stephanopoulis tapped one of the entry specialists on the shoulder and pointed at the door. The CQB swung again and the shield-and-shotgun team went up the stairs followed by a mixed half dozen from the Murder Team and the local Tactical Support Group. Their job would be to clear the top floors of the building while Stephanopoulis and I went downstairs.

I shone my torch down the shadowed depths of the staircase. They were carpeted with the kind of hard-wearing short-haired nylon carpet that you find in cinemas and primary schools. It was gold and red to match the flocked wallpaper. I got a strong sense of foreboding, which could have been vestigia or just a sensible reluctance to go down the creepy dark staircase.

We could hear the team working their way up through the building like a herd of baby elephants in a lumber yard. Stephanopoulis looked at me, I nodded, and we started down the stairs. We’d borrowed a pair of heavy-duty torches from the TSG, and their light illuminated a ticket office on the first landing. Beside it was an alcove with a counter and behind that was a yawning darkness that I hoped was just the cloakroom.

I went down cautiously, hugging the wall so I could get the earliest view around the corner—I seriously didn’t want anything springing out. The stairs doubled back, descending into more darkness and a door in the far side of the landing marked STAFF ONLY. I smelled mildew and rotting carpet, which was reassuring. I leaned over the cloakroom counter and shone my torch around the interior to reveal a shallow L-shaped room lined with rails and empty clothes hangers. I climbed over and checked inside. There were no coats or long-forgotten bags but there were bits of paper on the floor—I picked one up. It was a ticket stub. I walked around to the staff door and opened it to find Stephanopoulis staring warily down the stairs.

“Anything?” she asked. I shook my head.

She clicked her fingers and a couple of Murder Team detectives came padding down the stairs with gloves and evidence bags. Stephanopoulis pointed at the staff door and they dutifully trooped past me to do a more thorough search of the cloakroom. One of them was a young Somali woman in a leather biker jacket and an expensive black silk hijab. She caught me looking and smiled.