In a dystopian future where Earth's environment is ravaged and humanity has colonized other planets, the Tyrell Corporation has created replicants—bioengineered beings virtually identical to humans, designed for the hardest, most hazardous work in off-world colonies. These replicants are illegal on Earth and are hunted down and "retired" by special police operatives known as Blade Runners. When a group of Nexus-6 model replicants led by the intelligent and formidable Roy Batty escapes back to Earth, they seek a way to extend their pre-programmed four-year lifespans.

A tough and weary former Blade Runner, Rick Deckard, is coerced out of retirement to eliminate the four rogue replicants. As Deckard tracks the replicants through the decrepit streets of Los Angeles, 2019, he encounters Rachael, an experimental replicant with implanted memories that make her unaware of her non-human origins. The line between human and machine begins to blur for Deckard, who finds himself wrestling with profound questions about identity, emotion, and mortality, which complicates his mission.