(retitled Blade Runner: in some later printings) is a dystopian science fiction novel by American writer Philip K. Dick, first published in 1968. The novel 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 is tasked with 'retiring' (i. e. killing) 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 primary basis for the 1982 film Blade Runner and many elements and themes from it were used in the film's 2017 sequel Blade Runner 2049. Synopsis = Background and setting =In 1992 (2021 in later editions) following a devastating global war called World War Terminus, 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 violently rebel and escape to Earth, where they hope to remain undetected.