The streets were different at night too. Were colder, damper, and those who asked you for change did so in tones more aggressive than suppliant. The daylight hours taught them to know their place, and know it they did, and it was here, and now.

But she had a job to do. And once she was back on the street, Harvey would be waiting for her, bearing the thanks of a grateful Intelligence Service.

The office she was looking for was the largest on the floor, a corner suite. Ahead of her, the lights buzzed to life, and she knew that if she were observing this building from across the road, a story would be telling itself, one in which a lone woman—probably a cleaner—made her way through the night, scattering darkness as she went. But no one would guess her real mission. The door was not locked. She entered the room. It will take two minutes, no more. Harvey’s promise. Before the lights had time to turn themselves off, she would be on her way back to the stairwell. She approached the desk, on which a laptop sat, locked to its docking device with a chain sleeved in plastic. Two minutes. She reached into her pocket for the flash drive.

It was gone.

Whatever happens, you mustn’t let this fall into their hands.

She went through her pockets again—all of them. Even the ones the drive had never been in.

They mustn’t find it. I can’t tell you how crucial that is.

In her throat, a rising tide. It would all overcome her now, this mission she’d been chosen for, its importance, her own inconsequence. She could run away, hide under her bed, let the world go on without her. Except that that’s precisely what it would do, wouldn’t it? If she ran now, and failed in her mission, then the things Harvey had warned her about would happen, and the world would turn for the worse.

Once it’s done its job, you have to either get it out of the building, or hide it somewhere it won’t be found.

It hadn’t done its job yet, and it was still in the building. It must have fallen from her pocket, would be on the stairwell, or somewhere between this office door and the lobby, or else—

The toilet.

There, where she’d crouched for hours, waiting for the office block to grow quiet and dim. She’d all but frozen in place, and even now her arms and legs felt heavy. But before leaving she’d had a pee, and that must have been when it happened, must have been when the flash drive wriggled free from her pocket. How could she not have heard it? But that was a useless thread to follow. For now, the choice was stark. She could return to the lavatory on the eighteenth floor, or . . .