After the diplomatic failures of the Spacer mission on Earth-which began with the assassinations of key diplomats and politicians, and culminated with the uncovering of a vast plot to create cyborgs from terminally handicapped infants-Ambassador Ariel Burgess and roboticist Derec Avery are recalled to their home planet, Aurora. Unfortunately, their situation only worsens when they arrive, as they become suspects in yet another murder-one that, based on the evidence, could only have been committed by a non-human. On a world with a 20-to-1 robot-to-human population, is it possible a robot could have violated the Three Laws governing its behavior-and if so, why? Or is something far more sinister at worko?=?