They set off, Dreyfuss with his hands in his pockets and seeming to listen intently to what Hepton was saying, not that Hepton was saying very much other than reminding him of the layout of the tracking station’s interior. At the end of the path stood a hefty-looking steel door, and on the wall next to it a numerical keypad, topped by yet another video camera. Hepton tried to look nonchalant as he pressed home the combination 52339, then waited. There was a ca-chunk as the several locks on the door disengaged. He gave it a push, and they entered a sort of antechamber. Against one wall stood what looked like a clocking-in system, but instead of identifier cards, Dreyfuss saw that each slot held a plastic-coated name badge, and beside each name a photograph. Hepton reached for his own badge and tagged it to his trouser pocket. Dreyfuss took the first badge he saw and did likewise. He had been informed: Some guys clip them to their shirts, others to their trousers. If we tag them to our trouser pockets, there’s less chance of someone noticing that you’re not the face on the ID.

He had also been warned about the wall opposite this one, which was made of glass. Behind it, in a small room filled with video screens, sat another security guard. Hepton waved to the guard, who smiled and waved back, then pushed on through the interior door, Dreyfuss following mutely. Now they were in a long corridor, and walking briskly. Dreyfuss felt a kind of complete terror overtake him. They were getting deeper and deeper into this, almost too deep to facilitate any hope of escape. Hepton misread his companion’s fear.

‘Don’t worry,’ he said. ‘I reckon that with the shutdown, and the change of staff, nobody’s going to think a new face suspicious. In fact, we couldn’t have picked a better day, all things considered. The only thing that bothers me is that there are so many new faces, all of them probably connected to COFFIN. That guard back there, for instance. I’ve never seen him before in my life.’

Dreyfuss nodded his head. ‘So what if he checks up on us?’ He was trying to walk at the same pace as Hepton, but it was difficult not to fall a step or two behind and let him take the lead. After all, Dreyfuss had little idea where they were going. But he had to look as though he knew. He stared at the floor, matching his footsteps with those of his guide, and so concentrating grew less frightened and less nervous.

After a moment, he realised that Hepton hadn’t answered his question. The silence was answer enough in itself. Any check, and they’d be doomed. Suddenly a voice sounded behind them, and both men froze.