He reached the tent flap and eased himself through.

Firelight flickered, revealing all seven of the goum's tents arranged in a semicircle. The goats were clustered at the mouth of the semicircle, and beyond them were the camels, lying with their legs folded under them, spectrally pale, like mountains on a horizon.

To David's left lay the tent where the valuable merchandise was stored. The men on guard looked drowsy. Their rifles drooped towards the earth.

He couldn't risk sneaking past them, however. He would have to circumnavigate the camp and come at the camels from the far side.

He crept away from the campfire, out into the indigo dark. The terrain the caravan was crossing had changed recently. The landscape was no longer rocks and hard-packed earth, but sand, nothing but sand. Scooped, ribbed, undulating, supple sand, mile upon mile of it, wave upon wave. Sand that got everywhere: in your socks, in your hair, up your nose. David had even found grains of it under his foreskin.

Keeping the tents to his right he went in a broad semicircle, slithery-footed on the dune slopes. Finally he began his approach on the camels. He had already singled out the one he was going to take: an elderly male, so beaten and worn down that there was no more obstinacy left in it. This docile creature would, he reckoned, accept an inexperienced rider at the reins and not try to throw him off at the first opportunity.

He checked the sleepy guards again. As he looked, one of them gave in completely to tiredness and slumped to the ground. The man ended up in a sitting position, head bowed over the rifle in his lap.

The other guard turned and eyed his colleague. He muttered something to him, then went over and nudged him with a toe. The sleeping man didn't stir. Another, firmer toe-nudge sent him tumbling over onto his side in a loose heap. The second guard bent and rapped him on the cheek. He looked closer. He straightened up in alarm.