Torcred spun and ran, crouching, knowing the girl would follow. They plunged over the dune-top close together; the terrapin's gun wavered and did not fire, then its motor snarled into life and it bounded after them. Torcred, with Ladna close behind, ran panting down the windward slope, straight toward a cluster of domed, sunken structures. Sheer amazement of the pillbox-dwellers must have kept them alive so far; every moment he expected a murderous barrage. It came. The nearest pillbox erupted flame, and beyond it others. The explosions rolled flatly, echoless across the desert. Torcred caught the girl round the waist and flung her down beside him; hugging the ground, he raised his head slightly and looked back. The terrapin swerved agilely among spouting columns of sand. Then all its wheels left the ground at once, it tilted in the air and rolled over and over down the long slope of the dune. Black smoke poured from its punctured armor. VII Torcred stared long at the blackened wreck, hardly noting that the guns were silent, the haze settling. He knew none of the exhilaration that had been his when he took the panzer; a sickish sensation nested in his stomach. He had killed--by subterfuge, true, but killed all the same--a brother-terrapin, and now in his own mind rose up against him a lifetime's training, all the blood-ties with his own kind.... His own kind. The terrapins. But were they? _What was he?_ The breeze, laden with sharp smoke of explosive, made his eyes twitch and smart. He blinked, and saw the man standing on the dune's edge above them. Much nearer this time, so that there could be no doubt that the eyes were looking at him, that the lips smiled. That smile, and the careless stance that went with it, seemed to radiate confident power. Beside Torcred the girl gasped, and he knew with sudden relief that she too had seen the stranger. And so did the others. The bright air was split again by thunder as some touchy pillbox fired a shell. It struck squarely at the stranger's feet, and they saw him blown to fragments. But the burst drifted down the wind, things crawled and flickered in the air, and he was there again, smiling more broadly than before. He glanced aside, at the smashed terrapin, then back at Torcred, and raised his right hand in a gesture--thumb and finger forming a circle--that some of the desert peoples used as a sign of approval and encouragement. Then he rippled slightly, like a reflection in water, and was gone. Torcred was hardly conscious of how they squirmed out of range of the pillbox people's venomous annoyance. Ladna, brushing tangled black hair out of her eyes, was first to break the silence. "Was that what you saw yesterday?" "Uh-huh," admitted Torcred glumly. "But you saw. He wasn't real at all." "Did we see the same? He was blown to bits, and reassembled himself unhurt?" Torcred nodded. "Then there was something there."