The sun was setting when the two Martians reached the cliffs. Below them was the valley in which lay the metal sphere. Ro could see it dimly outlined in the shadows, as Na had said. A distance away, in another clearing, he could see many Oan, flitting ghost-like from place to place. There were no fires, for the Oan were more beast than man and feared flame; but Ro could make out four prone figures. They appeared to be white blots in the dimness. One had long, golden hair, like spun sunbeams; another's head was covered with a thatch like a cap of snow on a mountain peak. "You say they came from a place called Earth?" Ro asked Na in wonder. "They traveled through space in their 'ship,'" Na answered. "They called themselves an expedition." Ro was silent then. In a short time it would be dark enough to go down into the valley. When he had rescued the white ones, he would learn more about them. He turned away from the valley to study Na. She was very beautiful. Her dark eyes seemed to sparkle and her hair shone in the twilight. He understood why she had crept into his dreams. The darkness settled quickly. Soon Ro could barely make out the girl's features. It was time for him to leave. He took a pouch from his waist and shook out a gold arm band. This he clasped on Na's wrist. "All men will know now that you are the mate of Ro," he whispered. And he kissed her, as was the custom of his tribe when a man took a wife. Without another word he disappeared over the edge of the cliff. They had already made plans for their next meeting. There was no need for a prolonged farewell. They would be together soon--on the far side of the cliff--if all went well. In his left hand and under his armpit Ro carried stones. They were of a good weight and would make short work of any Oan who was foolish enough to cross his path. His right arm he kept free for climbing. His fingers found crevices to hold to in the almost smooth wall. His toes seemed to have eyes to pierce the darkness in finding footholds. * * * * * The climb was long and dangerous. Ro's skin glistened with sweat. He had lived in the cliffs all his life, and had made many perilous climbs, but never one on so dark a night. It seemed an eternity before he rested at the bottom. Feeling his way cautiously, he moved toward the camp. He could sense the presence of many Oan close by. The hair at the base of his neck prickled. He prayed he wouldn't be seen. An alarm now would spoil his plan. Ahead of him, he saw a clearing. That would be his destination. On the far side he would find the white ones. He took the stone from his armpit and moved on. Suddenly he halted. A dim figure approached. It was one of the Oan, a guard. He was coming straight at Ro. The young Martian shrank back. "The rat men have eyes to cut the night." It was a memory of his mother's voice. She had spoken those words when he was a child, to keep him from straying too far.