He could see the wall they pressed against running ahead before smoothly turning to the right in a curve so sharp he couldn’t see anything ahead of it. In front of him, all around, there was nothing. Nothing at all. Empty space met the eye as far as it could see, space filled with the same white-blue light he’d spotted leaking through the crack in the wall. He could feel the emptiness, the complete lack of anything under the tips of his shoes. The ledge was now so narrow that his feet were sticking out. And to make matters worse, the very surface they stood on was loose and crumbling, with every step they took little bits of rock dislodged and fell into—into what? Below the ledge, there was nothing—just emptiness, and a sheer drop so far down he couldn’t see the bottom. To his right, Kieran had his arms stretched out flat against the wall. His feet were even further off the ledge than Albert’s, the look of concentration on his face not quite masking the panic in his eyes, blinking every so often in an effort to keep out the beads of sweat collecting around them.

How ironic, he thought, if he were to escape Bosquanet, the lawbots and SUE only to plummet to his death here, where every step was a new opportunity to kill oneself. Come to think of it, SUE would have probably loved it here. A million and one opportunities to commit suicide, which was no doubt its version of machine heaven. He, on the other hand, had every intention of not falling. All right, focus now. One step at a time. Slowly.

Albert had experienced many excruciating moments already, but nothing that quite compared to the deliberate, unbearable anguish of this hellish journey. Slowly, torturously, they moved ahead, inch by agonizing inch, not daring to look away, or down or anywhere but at the person in front, never knowing which step would be their last.

Somehow, though, they managed, ever so gradually moving forward, so they were now curving with the wall and round the other side. He could see the ledge widening some way ahead, dipping in a gentle slope to meet a clearing among the rocks around.

And then it happened. He heard a shout—a single wordless, almost animal, cry of alarm. He felt a hand slap his ear, scrabbling frantically against the rock. He turned and saw Kieran—face wide with shock, fear in his eyes, arms flailing against the wall, claw-like fingers clutching in vain for a handhold as his left foot slipped through the gaping hole underfoot where the ledge had given way.