A man without memory named Derec, and a mysterious woman known as Ariel are trapped on the confusing, surprising, and sometimes deadly world of Robot City. Having solved the murder of an unknown human and proven to the robots that they are innocent, Derec and Ariel are faced with ever-growing emergencies. They discover that the City contains a cyborg that is dangerously insane, and learn of a new form of self loathing called roboticide. Derec learns that Ariel is stricken with a disease that leads to fatal madness, and both are startled to learn that the robot's positronic consciousness has given rise to artistic expressions even as the City itself grows ever more deadly to all of its inhabitants. The late Isaac Asimov challenged a talented group of science-fiction writers to resolve the conundrums he set for them in the complex robot mystery set early in the timeline of his robot and Foundation universes.