In the future, humans have developed android slaves to do all sorts of hard work in off Earth colonies. The androids are also called "replicants" and are banned on Earth. Special police personel called "Blade Runners" hunt down and destroy replicants on Earth, a process called "retirement".
A new superior generation of replicants, the Nexus6, has been developed at the giant coorporation Tyrell Corp. Nexus6 replicants are super intelligent and have the capability of developing emotions of their own which is why they have a short life span of only four years. A group of four Nexus6 replicants have made it to Earth in a violent and dramatic way. The replicants have become aware of their short life span and are seeking the leader of Tyrell Corp. who made them.
The top Blade Runner, Deckard, is assigned to hunt down the group of four replicants. He visits Tyrell Corp. and there he conducts the VK-test on a woman called Rachel. The VK-test is developed to detect replicants during an interview. Deckard uses the VK-test to reveal that, to Rachel's shock, she is in fact a replicant. Rachel has been implanted false childhood memories and did not know she was a replicant. Rachel and Deckard eventually get closer attached to each other and fall in love even though Deckard, as a Blade Runner, should retire Rachel. She suspects something of Deckard and asks him if he ever took the VK-test, but she gets no answer from him.
The powerfull replicant Roy is the leader of the group of four replicants that escaped from the off world colonies to Earth. During the hunt for the four replicants, Deckard witnesses a development in the personality of Roy which is quite surprising...