Called to the Spacer world to solve a case of roboticide, New York City detective Elijah Baley teams up with humanoid robot R. Daneel Olivaw. Together they are tasked with proving that the prime suspect, a renowned roboticist, is innocent of the crime. Plain clothes man Elijah Baley must travel to the planet Aurora to investigate the murder of Robot Jander. He would rather not. His last trip off-Earth on police business resulted in a TV drama being made of the case - as a result of which even his son Bentley suspects Elijah had an affair with Gladia Delmarre, the murder suspect whom he proved innocent. Not only does Gladia now live on Aurora, the murdered robot belonged to her...and was her lover! Elijah is teamed once more with Robot Daneel, and they are joined by another interesting robot, Giskard. The investigation should benefit from a secret and unique ability possessed by Robot Giskard. But Elijah is disturbed by his presence, sensing perhaps that Giskard's positronic brainpaths function to a hidden agenda. What Giskard knows but Elijah does not is that the future of mankind in space hangs on the outcome of this investigation...