Rick Deckard, a retired cop of the Los Angeles Police Force, is summoned back to work to help find and destroy escaped Replicants who pose a threat to the rest of humanity. Replicants were originally created by the Tyrell Corporation in the same design as humans to act as slaves on Earth and in the off-world colonies. Some of these Replicants are originally used to explore new off world colonies, but a bloody battle ended one such exploration and caused them to be left to exist on a colony by themselves. They have a tendency for violence and super-human qualities: superior strength, agility and equal intelligence to that of humans. Their life span was only four years and it was believed they would die out, ending any threat to mankind.

Four Replicants somehow manage to hijack a ship from another colony, kill its occupants...