When they had been walking for eternity and six days longer, as Alan judged it, figures appeared below the huge disk, coming down the inclined steps or plane in the crystal bubble, grouping on the ground. The Earthmen were then just over an eighth of a mile from the ship. The aliens looked human; it was difficult to see differences in their structure and that of a man; and they wore clothing that glistened as they moved in the sun. They were setting up three small pieces of machinery beneath the disk. Alan could not guess what they might be. Then the men in the lead, Brave and Bill and Alan, ran into an unseen wall that knocked them staggering from the force of their own motion. The aliens had set up a screen around their ship. "Here's where I yell out the plan, I guess," said Brave ruefully. "The plan is to make faces, men. That seems to be the only thing we can do of a warlike nature. God, a force wall! We might have known." * * * * * Alan, who had sat down abruptly when he struck it, jarring the tied-down cat on his shoulder and causing her to sink her claws through the coat into his skin with anger, stood up and felt the air before his face. "Amazing. Touch this thing, you fellows. It feels like a sheet of hard rubber. It's perfectly tangible. I can almost feel a grain in the thing." "What scientists they must be!" exclaimed Rob Pope. "This--hey!" he shouted, startled. "Here's an opening!" Then he had walked on across the bowl. Bill Thihling, nearest him, tried to follow. He found there was no hole there. He skinned his nose on the force screen. "Rob's crazy," he said. "He thinks there ain't no force wall there. So he walks through it. Only a loon could do it." Pope came back. "I heard that. What the hell...? It was here a minute ago." "Can't you get back?" "No! The wall's solid again. By Jupiter, they let me come through; they wanted to see one of us at a time. All right, I'll play their game." He wheeled and marched straight toward the disk. "Oh, Rob, come back!" screamed Win. "They'll do something awful to you!" "Too late now," said Alan, taking her arm. "They've caught him in their cage like a rabbit." "A fanged rabbit, anyway," said Don. "He's got his guns." Rob walked under the silver ship, into its shadow. The aliens clustered about him. Beyond the wall of force, the men and the girl held their breath tensely. After a minute or two, "Why," said Jim McEldownie, "they haven't even taken away his rifle!" Shortly Rob turned his face toward them and waved. It was an encouraging motion. Whatever was happening did not seem hostile.