He came to the top of the rise, and the ground levelled out. He got the feeling that in daytime it would make a bleak picture. There was nothing here but stunted wilderness, hardly fit for the hardiest sheep. Way ahead a shadow rose into the sky, some hill-range or other. The wind, which had dried his shirt but chilled him to the marrow, now dropped. Jesus, his head was hurting. Like sunburn but a hundred times worse. He stared up at the sky. The outlines of the clouds were visible. The weather was clearing. A sound had replaced the whistling of the wind in his ears.

The sound of running water.

It grew louder as he moved forwards. He had lost Knox’s torchlight now, and was conscious of being alone; conscious, too, that if he strayed too far, he might not find his way back. A route wrongly taken could leave him heading towards nothing but hill and forest. He glanced back. The line of trees was still just about visible, though the house lights beyond were not.

‘Jack! Jack!’ Knox’s voice seemed miles away. Rebus decided that he would skirt round towards it. If Gregor Jack was out there, let him freeze to death. The rescue services would find him tomorrow . . .

The running water was much closer now, and the ground beneath his feet was becoming rockier, the vegetation sparse. The water was somewhere below him. He stopped again. The shapes and shades in front of him . . . they didn’t make sense. It was as if the land were folding in on itself. Just then, a huge chunk of cloud moved away from the moon, the large, nearly full moon. There was light now, and Rebus saw that he was standing not four feet from a sheer drop of five or six yards, a drop into a dark, twisting river. There was a noise to his right. He turned his head towards it. A figure was staggering forwards, bent over nearly double from exhaustion, its arms swinging loose and almost touching the ground. An ape, he thought at first. He looks just like an ape.

Gregor Jack was panting hoarsely, almost moaning from effort. He wasn’t watching where he was going; all he knew was that he had to keep moving.

‘Gregor.’

The figure wheezed, the head jerking up. It came to a stop. Gregor Jack rose to his full height, arching his head to the sky. He lifted his tired arms and rested his hands on his waist, for all the world like a runner at the end of his race. One hand went instinctively to his hair, tidying it back into place. Then he bent forwards and put his hands on his knees, and the hair flopped forwards again. But his breathing was becoming steadier. Eventually he straightened up again. Rebus saw that he was smiling, showing his perfect teeth. He began shaking his head and chuckling. Rebus had heard the sound before from people who’d lost: lost everything from their freedom to a big bet or a game of five-a-side. They were laughing at circumstance.