Endor met him out the back of the dance club just after one in the morning, and exchanged the cash for a slip of paper.

Mira Zaleed, 870 Arbogan.

He considered leaving it until the morning, but he was restless, so he bought a quart of amasec at a tavern on Oroshbyli Street, and rode the maglev to Corso Saint Helk in the north of the city. From the station, it was a long walk up the rockcrete walkways to the hab blocks: Solingen, Zarbos, Arbogan.

The stairwells were unlit, and choked with trash. A domestic quarrel was raging on the fifth floor, and the residents of other habs were yelling out protests at the noise. Just before he located 870, it occurred to him that 870 was twice 435.

Titus Endor stood in the gloomy hallway, listening to the racket of someone else’s private life disintegrating, and wondered if the numbers were significant. Numbers could be dangerous. A life of study and an eventful career had shown him that. Certain numbers, usually abstract mathematical constructs, possessed power. He’d heard of several cases where cogitators had been corrupted by warped numbers, and he’d been party to another case, years ago, when some old fool had mistakenly believed he’d uncovered the Number of Ruin. He and Gregor had handled it, and it had come to nothing, but they’d taken it seriously. He couldn’t remember the old fool’s name now, some dusty scribe, but he remembered the case. They’d been interrogators then, him and Gregor, just starting out. They’d been friends.

An age ago, in another life.

His mind had wandered. He blinked, and wondered how long he’d been standing in the dim passageway outside 870 Arbogan. The domestic had ended, and the night was still. From somewhere, he heard the frail sound of zendov music, playing on an old voxcordian.

He decided to steady his nerves with a sip of the quart of amasec, and discovered that the bottle was half-empty already.

He knocked on the door.

There was no answer. Someone in a neighbouring flat cried out, the half-awake mew of the nightmared.

He knocked again.

‘Mira Zaleed?’ he called.

The door was baffled shempwood in an iron frame, with double dead-bolts and a triple-tumbler, Blaum et Cie safety lock. The lock had been retrofitted into the door, an expensive piece of kit for such a low-rent hab. He rummaged in his trouser pocket, and found his anykey. The slim blade extended from the grip, slipped into the lock, and muttered as it explored the permutations.

He waited. One murmur more, and the anykey turned. The lock sprung with a clatter of rotating drums, and the deadbolts unlatched.

He put the anykey back in his pocket and pushed the door open with his toe.

‘Mira?’