Once they were out of sight, Saul pressed a fingertip to his temple to call up a menu within his iris. It appeared as a small screen apparently floating off to one side ahead of him, and he scrolled down it by sliding his finger lower, selected something with another press of his fingertip and continued searching. Skin nerves at his temple, linked to the processor embedded in the bone lying underneath, acted like a fine-tuned ball control. Finally he found the blueprint of this building, the diagram appearing to him on a large square virtual screen seemingly rising out of the floor just a few paces ahead. After reminding himself of the layout, he shut the thing down and quickly headed for a nearby bank of lifts, which took him down into the basement.

As he stepped out of the lift, an immediate drop in temperature sent a shiver down Saul’s spine. Ahead lay a long corridor lined with doors opening into the mapping rooms, which in turn opened into the main store of deep-frozen cylinders containing the DNA samples waiting to be mapped. To his right a short corridor terminated at the door leading to the combined library and control room. Opening his holdall to take out one particular item, Saul strode over, pushed the door open and entered.

Aiden King sat at a line of consoles, a big display screen above him running graphics charting the progress of the mapping computers, one frame open on something he had obviously been working on – clearly some sort of presentation. Behind him lay the door into a staff toilet, beside which stood a vending machine filled with Food Agency approved drinks, low-sugar chocolates and plastic-wrapped sandwiches.

Saul glanced up at a security camera set high in the wall, but if Janus hadn’t dealt with that by now it was simply too late. King was taking a break, eating a grey-looking sandwich, his feet up on the console. He abruptly dropped his feet to the floor, tossed his sandwich back on to his plate and sat upright.

‘Citizen Avram Coran?’ he said, obviously surprised. The Inspectorate Assessor wasn’t due for half an hour, but it was not unknown for government officials to turn up early to start throwing their weight around.

‘He’s not here yet,’ Saul said mildly, heading over towards the man.

King began to stand, still looking slightly bewildered, then dumbfounded when he saw his own name on the tag Saul wore. Too late. The space between them hazed and crackled with energy. King jerked upright, stiff as a flagpole, miniature lightnings skittering over his lab coat and earthing from his shoes into the floor. Eyes rolling up into his head, he toppled like a falling tree and slammed down on his back with wisps of smoke rising from his clothing, a smell like burnt wiring permeating the air.