Then he selected his route, and slipped away.

MacConnachie was furious and baffled. The helicopter had reached the pimple and clearly had not sighted Ansell. It began to search in wider and wider arcs of flight.

‘What are you playing at, you stupid little bastard?’

But nothing happened, and MacConnachie raged. Had he seen Ansell’s manoeuvre, he would have admired it. But had he looked, he would not have seen it; light made little difference to Ansell’s gift of invisibility.

‘Oh, goddammit, run – run!’

It suddenly dawned on Ansell that he was clean away. He had only to keep going, and they would never find him. But it wasn’t true, he knew. He was free now because MacConnachie had freed him. Once it got tough again, he would need MacConnachie’s blundering resolution to save him. All the same, he felt an enormous flush of satisfaction.

As soon as the chopper came near, he showed himself. He ran a little to the left, stumbled, turned back and ran to the right. When he was sure he had created a convincing impression of panic, he set out across MacConnachie’s front, aiming for a point between MacConnachie’s firing position on his left and the pimple on his right. Without the canteen, he ran much more easily.

‘Oh, you clever little perisher,’ murmured MacConnachie, chuckling, ‘you fly bastard.’

He brought the gun up and checked the sights. Less than two hundred yards, open-sight firing. That meant three snap shots, close together, correcting on each shot. Four seconds shooting, one chopper to bag. You’re joking, of course.

Ansell was going like the clappers, stretching out like a lover with a shot-gun up his tail. No canteen. Check that after. The helicopter came round, falling in behind him.

MacConnachie was sure the pilot would be raging by now, determined to buzz Ansell savagely. There was no doubt he was coming in far too low. Carelessly low. Beautifully low.

MacConnachie held the gun gently until it was part of him, taking a long, slow breath. Fifty yards to come.

Ansell was tiring rapidly, gulping air, driving himself to maintain pace. His cheeks seemed to have swollen to the size of balloons, and as he bounced up and down they flapped in and out of his lower field of vision like white dewlaps of blubber. The demoralizing illusion came to him again that he was getting nowhere, and the terror, far from being pretended, was now real. The chopper was low. Too low. It was going to hit him. The swishing, chilling whine paralysed him. He was going to be hit. Hit. There’s the pimple. Go left. Turn. Stumble. Ankles crack together. Stay upright. Stay upright.

Perfect. Coming in just right. The kid still fifteen feet ahead, not flagging. He’ll have to go like the devil when that thing explodes.

Vaguely aware somebody leaning out of the cab. Must be the observer. Pilot on the other side. Could get a shot in now. Wait. Wait.

Breaking in towards me. Lovely. Well done. Here comes the chopper. Dip, you bastard. Dip. That’s better. Bit more. Bit more…