They could eat wood if necessary. They had sub-dermal pigmentation sacs which gave them natural camouflage.

They were stronger, faster and cheaper to mass produce than comparable human soldiers. At least such was the hope. These were the field trials, he was the observer.

The Greens had clustered around something, watching with alert fascination. He strolled over to look. On the ground a raiding party of ants were locked in combat with a large beetle several times their size.

The beetle was massively armoured with huge jaws but it was doomed; the ants swarmed over it spraying formic acid.

Travis watched the reactions of the Greens closely. Bill-boy smiled and nodded happily, Carlo shook his head and walked away. Chad's face might have been carved from stone for all the expression it carried. Stef looked puzzled.

"Watch them," Saunders, the CIA man, had said back in the Camp. "Anything unusual, no matter how trivial, report it."

The ants had finished the beetle. Bill-boy stood up and looked around pleased. Then he brought his foot down and ground the ants under his heel.

He smiled.

"Let's eat," he said. Travis stared at him. A prototype, he reminded himself. He's just a prototype. A small, mocking voice inside his own head said just like you were. His feelings of unease increased.

4. Ambush.

The Sandinista never knew what hit them. They had been following the trail, straggling along in a line, three men on point. Travis had let them go ahead until the main body of troops were over the anti-personnel mines which he had seeded the trail with.

Travis detonated the mines himself because they were a weapon he hated, had done ever since Beirut.

Men were torn apart by the small explosives. The rest were shocked and disorganised. They fell to a hail of fire from the American assault rifles.

Some of those at the back escaped the mines and dived for cover, firing a fusillade of shots into where they thought the enemy were. They hit their own men for the most part. Travis and the Greens quickly flanked them and chopped them down.

In the confusion a young boy armed with a bayonet leapt on Travis from the undergrowth. Travis desperately deflected the blade with a sweep of his arm. He saw the look of horror on the boy's face when his knife bounced drawing no blood. Travis stood there looking at him, trying in that moment to forget the brief flash of human contact as their eyes met and bring his gun round. The boy drew his rifle back for a second swing.

The boy went down. Chad's long knife protruded between his shoulder blades. Chad showed him a wolf grin then turned to pursue the fleeing humans.