Background and setting
Following a devastating global war in what was then the near future, the Earth's radioactively polluted atmosphere leads the United Nations to encourage mass emigrations to off-world colonies to preserve humanity's genetic integrity. Moving away from Earth comes with the incentive of free personal androids: robot servants identical to humans. The Rosen Association manufactures the androids on a colony on Mars, but some androids rebel and escape to Earth, where they hope to remain undetected. American and Soviet police departments remain vigilant and keep android bounty-hunting officers on duty.
On Earth, owning real live animals has become a fashionable status symbol, both because mass extinctions have made authentic animals rare and because of the accompanying cultural push for greater empathy. Poor people can only afford realistic-looking robot imitations of live animals. Rick Deckard, the novel's protagonist, for example, owns an electric black-faced sheep. The trend of increased empathy has coincidentally motivated a new technology-based religion called Mercerism, which uses "empathy boxes" to link users simultaneously to a virtual reality of collective suffering, centered on a martyr-like character, Wilbur Mercer, who eternally climbs up a hill while being hit with crashing stones. Acquiring high-status animal pets and linking in to empathy boxes appear to be the only two ways characters in the story strive for existential fulfilment.
Plot summary
Rick Deckard, a bounty hunter for the San Francisco Police Department, is assigned to "retire" (kill) six androids of the new Nexus-6 model which have recently escaped from Mars and traveled to Earth. These androids are made of organic matter so similar to a human's that only a "bone marrow analysis" can prove the difference, making them almost impossible to distinguish from real people. The analysis is painful and lengthy, and is in most cases posthumous. Deckard hopes this mission will earn him enough money to buy a live animal to replace his lone electric sheep to comfort his depressed wife Iran. Deckard visits the Rosen Association's headquarters in Seattle to confirm the accuracy of the latest empathy test meant to identify incognito androids. Deckard suspects the test may not be capable of distinguishing the Nexus-6 models from genuine human beings, and it appears to give a false positive on his host in Seattle, Rachael Rosen, meaning the police have potentially been executing human beings. The Rosen Association attempts to blackmail Deckard to get him to drop the case, but Deckard retests Rachael and determines that Rachael is, indeed, an android, which she ultimately admits.
Deckard meets a Soviet police contact who turns out to be one of the Nexus-6 renegades in disguise. Deckard kills the android, then flies off to kill his next target, an android living in disguise as an opera singer. Meeting her backstage, Deckard attempts to administer the empathy test, but she calls the police. Failing to recognize Deckard as a bounty hunter, the cops arrest and detain him at a police station he has never heard of, filled with officers whom he is surprised to have never met. An official named Garland accuses Deckard of being an android with implanted memories. Garland, pointing a gun at Deckard, reveals that the entire station is a sham, claiming that both he and Phil Resch, the station's resident bounty hunter, are androids. Resch shoots Garland in the head, escaping with Deckard back to the opera singer, whom Resch kills in cold blood when she implies that he may be an android. Desperate to know the truth, Resch asks Deckard to administer the empathy test on him. The test indicates Resch has sociopathic tendencies but confirms he is human. Deckard then tests himself, confirming that he is human but has a sense of empathy for certain androids.
Deckard is now able to buy his wife Iran an authentic Nubian goat with his commission. Later, his supervisor insists that he visit an abandoned apartment building where the three remaining android fugitives are assumed to be hiding. Experiencing a vision of the prophet-like Mercer telling him to proceed, despite the immorality of the mission, Deckard calls on Rachael again since her knowledge of android psychology may aid his investigation. Rachael declines to help, but reluctantly agrees to meet Deckard at a hotel in exchange for him abandoning the case. At the hotel, she reveals that one of the fugitive androids is the same model as her, meaning that he will have to kill an android that looks like her. Despite having initial doubts by Rachael, she and Deckard end up having sex, after which they confess their love for one another. Rachael reveals she has slept with many bounty hunters, having been programmed to do so in order to dissuade them from their missions. Deckard threatens to kill her but ultimately holds back and leaves for the abandoned apartment building.
The three remaining android fugitives plan to outwit Deckard. The building's only other inhabitant, John R. Isidore, a radioactively damaged and intellectually below-average human, attempts to befriend them. He is shocked when they callously torture and mutilate a rare spider he discovers. They all watch a television program which presents definitive evidence that the entire theology of Mercerism is a hoax. Deckard enters the building, experiencing strange, supernatural premonitions of Mercer notifying him of an ambush. When the androids attack him first, Deckard is legally justified as he kills all three without testing them beforehand. Isidore is devastated and Deckard is rewarded for a record number of Nexus-6 kills in a day. Returning home, Deckard finds Iran grieving because, while he was away, Rachael stopped by and killed their goat.
Deckard travels to an uninhabited, obliterated region of Oregon to reflect. He climbs a hill and is hit by falling rocks, realizing this is an experience eerily similar to Mercer's martyrdom. He stumbles upon what he thinks is a real toad (an animal thought to be extinct) but, when he returns home with it, he is crestfallen when Iran discovers it merely is a robot. As he goes to sleep, she prepares to care for the electric toad anyway.
