He reached the lip of the basin where the water poured over in a cataract several hundred feet high. Climbing around the shoulder of a rocky bastion, Trevor had his first clear look at the valley. Much of it was still vague with mist. But it was broad and deep, with a sweep of level plain and clumps of forest, locked tight between the barrier mountains. And as he made out other details, Trevor's astonishment grew out of all measure. The land was under cultivation. There were clusters of thatched huts among the fields, and in the distance was a rock-built city, immense and unmistakable in the burning haze of dawn. Trevor crouched there, staring, and the winged lizard swung in lazy circles, watching, waiting, while he tried to think. A fertile valley such as this was rare enough in itself. But to find fields and a city was beyond belief. He had seen the aboriginal tribes that haunt some of the cliff-locked worlds of the Twilight Belt--sub-human peoples who live precariously among the bitter rocks and boiling springs, hunting the great lizards for food. None of this was ever built by them. Unless, in this environment, they had advanced beyond the Age of Stone.... The gong sounded again its deep challenging note. Trevor saw the tiny figures of mounted men, no larger than ants at that distance, come down from the city and ride out across the plain. Relief and joy supplanted speculation in Trevor's mind. He was battered and starving, lost on an alien world, and anything remotely approaching the human and the civilized was better luck than he could have dreamed or prayed for. Besides, there were sun-stones in this place. He looked hungrily at the head of the circling watcher, and then began to scramble down the broken outer face of the bastion. The black wings slipped silently after him down the sky. * * * * * About a hundred feet above the valley floor he came to an overhang. There was no way past it but to jump. He clung to a bush and let himself down as far as he could, and then dropped some four or five yards to a slope of springy turf. The fall knocked the wind out of him, and as he lay gasping a chill doubt crept into his mind. He could see the land quite clearly now, the pattern of the fields, the far-off city. Except for the group of riders, nothing stirred. The fields, the plain were empty of life, the little villages still as death. And he saw, swinging lazily above a belt of trees by the river, a second black-winged shadow, watching. The trees were not far away. The riders were coming toward them and him. It seemed to Trevor now that the men were perhaps a party of hunters, but there was something alarming about the utter disappearance of all other life. It was as though the gong had been a warning for all to take cover while the hunt was abroad.