In a war against robots, the robots try to find a way to break the human defenses by sending a robot spy disguised as a human. The spy leads them into a trap, and they discover that their spy was a human disguised as a robot.
A cruel boss of native pearl divers, Mason, tries to out-dive a stranger who has appeared on the island so that he will not lose face in front of the natives, but the stranger, named Kor, is a water-breathing alien who easily outlasts him.
A scientist prolongs his life for a thousand years, outliving all his friends as Earth becomes overpopulated. When Earth is abandoned he stays behind with one young woman, leaving only the two of them, Adam and Eve, to restart civilization.