The main plot follows Rick Deckard, a bounty hunter who is faced with killing ("retiring") six escaped Nexus-6 model androids, while a secondary plot follows John Isidore, a man of sub-par IQ who aids the fugitive androids. In connection with Deckard's mission, the novel explores the issue of what it is to be human. Unlike humans, the androids are claimed to possess no sense of empathy.