Before he could put it into operation, though, he had to make sure he was free of any other little surprises that Harry Chain might have adhered to him. He needed a back-street electronics chop shop that would take his money without asking questions. Fortunately, in the shadow of the huge domik pile, such establishments were two a cent.

He negotiated the purchase of a sweeper, and got the shopkeeper to throw in a battery and a demonstration of how the lipstick-sized device worked. He paid for it with the last of the money on his card, unwrapped the tiny black wand there and then, and swept himself in front of the counter.

He was clean, from the white-blond hairs on his head to the worn soles of his feet.

The sweeper went on a lanyard around his neck and under his shirt. He shouldered his bag, and crossed the road. There were cameras at the junction, looking down at the crowds that swarmed back and forth. He looked up and fixed one with a knowing stare. The next time he passed that way, the computers that could isolate and recognize a face would put a different name to his.

He kept on walking until the pyramid of domiks showed its entrance, shaped like an ancient megalith: a tunnel constructed of upright containers with others braced on top to create a space that was as high as a cathedral, the main street that pierced the core of Regent’s Park. Sodium lights hung from above and burned orange, illuminating the hawkers, the whores and the hustlers who bought and sold everything and anything.

It was like the Nevskiy Prospekt during the darkest days of Armageddon. Winter, freezing Arctic winds howling down from Siberia, the bass rumble of generators and babble of voices, flashes of light and color, the whisper of rumors—they have bread, that stall sells poisoned vodka, those fish are radioactive—the stench of struggle. The good old days when he ran wild through the unlit streets, stealing books and candles.

He kept on through the market bustle until he got to the Inner Circle, a distribution road in the very heart of the pile. Some people, driven by madness or guilt, would walk the Circle until they dropped. There were others who would wait for them and then strip the corpses, and others still wouldn’t wait even that long.

Regent’s Park was like that.

Petrovitch found Staircase Eight and started climbing. He kept climbing until the stair-dwellers dwindled to nothing and the corridors were empty. There was one last bulkhead light, then nothing but blackness. He reached into his bag for a tiny key ring torch.

The blue light was no more than a bubble, but it was enough to see by. He walked on until he was blocked by a door equipped with a mechanical combination lock. He held the torch in his teeth and slid the lock cover aside.