Do Androids Dream of Electric Sheep by Philip K Dick

Do Androids Dream of Electric Sheep? (retrospectively titled Blade Runner: Do Androids Dream of Electric Sheep? in some later printings) is a 1968 dystopian science fiction novel by American writer Philip K. Dick. It is set in a post-apocalyptic San Francisco, where Earth's life has been greatly damaged by a nuclear global war, leaving most animal species endangered or extinct.

The main plot follows Rick Deckard, a bounty hunter who has to "retire" (i.e. kill) six escaped Nexus-6 model androids, while a secondary plot follows John Isidore, a man of sub-par IQ who aids the fugitive androids.

The book served as the basis for the 1982 film Blade Runner and, even though some aspects of the novel were changed, many elements and themes from it were used in the film's 2017 sequel Blade Runner 2049.

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.