Blade Runner is set in a dystopian future Los Angeles of 2019, in which synthetic humans known as replicants are bio-engineered by the powerful Tyrell Corporation to work on off-world colonies. When a fugitive group of Nexus-6 replicants led by Roy Batty escapes back to Earth, burnt-out cop Rick Deckard reluctantly agrees to hunt them down.

References:
https://en.wikipedia.org/wiki/Blade_Runner