Eleanor squatted, her backside below the surface of the water. Growing cold. Teddy lobbed the grenade out across the meadowland. Crouching down. Five seconds later there was a barely audible thud.

Another line of posts rose out of the ground ahead of them. Eleanor could hear grass and soil ripping. This time there were no red lights on top.

Suzi and Teddy took aim with their AKs.

PRESSURE-SENSITIVE PICKET, said the graphics, when she asked. There were another two picket lines between them and the forest. The memory core didn't have any information about what they did if you walked between them. Presumably, if you were talented enough to be on this kind of mission you ought to know.

They yomped on.

The stream's banks were growing perceptibly steeper. Eleanor thought the water was getting deeper too. Her view across the meadowland was shrinking. Thick patches of watercress choked both sides of the stream. Roddy and Nicole had to walk through it, kicking away a tangled wrap of tendrils from their legs every few paces.

Eleanor was glad of the brief rest when they came to the next picket line.

Victor pressed his head up to hers. "You OK?"

The AKs demolished another set of pillars.

"Fine."

There was a quick squeeze on her upper arm.

Suzi and Teddy reloaded their carbines, jamming in fresh magazines with hard snaps.

The stream fell on harder rock. It was narrower now, deeper. The water came up to Eleanor's knees, Teddy slowed the pace, edging cautiously round the sharper turns.

"How about a couple of us walk along the side?" Suzi said. The banks had risen until they were level with Eleanor's head. She couldn't see much of the meadowland now. What was visible seemed to be small deep hollows, and ground-hugging bushes. There could've been anything hidden out there. Her breathing was coming faster.

"No," Teddy said.

Suzi didn't argue. Discipline, Eleanor thought it would've made a lot of sense to have someone who could look out over the meadowland.

They rounded a bend and saw the last line of picket pillars had already emerged from the earth. Five AK carbines came up in reflex. There was a moment's pause.

The sentinel came at them through the air like a guided missile. Eleanor saw it as a pink streak arcing overhead, forelegs at full stretch, an angel of death reaching for Des. All five AKs opened up, filling the air with a guttural roar. Des was falling backwards, still firing. The sentinel's heavy streamlined body juddered in mid-flight, its edges distorting as the slugs chewed it apart. Momentum kept it going. Des hit the water. Eleanor's image was suddenly degraded by a spray of blood painting her hood's photon-amp receptors. The sentinel landed almost on top of Des, already dead.

"Keep watching!" Teddy bellowed as they all began to move towards the carcass.