WARNING: Contains nothing but spoilers
In the future, scientists developed a race of Artificial Humans called "Replicants." The Replicants were made to take on tasks and jobs thought too dangerous and physically draining for humans, and as such were made to be stronger, more enduring and resilient and capable of quicker thinking, than the average human being, while at the same time subservient to humans. However, several incidents with Replicants violently rebelling against their programming led to a world-wide ban on them, their use only being allowed on off-world colonies. But following a ongoing global climate disaster that started seriously affecting the Earth in the early 2020s, things were getting desperate as world society at large started lacking human workforce, and when the upstart Wallace Corporation, which had bought out the ailing Tyrell Corporation, which previously was mainly responsible for producing and developing replicants, introduced a new generation of replicants, who proved much more obedient than any generation before it, the ban was lifted.
One such Replicant is Officer KD6-3.7, or just "K" for short, who works as a "blade runner" for the LAPD, his job being hunting down and "retiring" rogue older model replicants. His home life is spent with his holographic girlfriend Joi, an artificial intelligence product of the Wallace Corporation.
K's investigation into rumors about a growing Replicant freedom movement leads him to a farm, where he confronts the rogue Replicant Sapper Morton. After a short but violent fight, K defeats Morton, who uses his last words to curse K for being a Hunter of His Own Kind, telling him that the new generation of Replicants have no idea what it means to be human, as they have never "witnessed a miracle." K then retires Morton, but as he is about to return home, a dead tree outside Morton's farm catches his attention, and upon closer investigation of the ground around the tree he finds a buried box. Forensic analysis reveals the box contains the remains of a female Replicant who died as the result of complications from an emergency caesarean section. K finds this unsettling as pregnancy in Replicants was originally thought to be impossible.
K is ordered to destroy all evidence related to the case and to retire the child by his superior, Lieutenant Joshi, who believes the knowledge that Replicants are able to reproduce could be dangerous, as it would be taken as a sign that the line between humans and Replicants is blurring, and therefore could lead to war. K, disturbed by his orders to kill a born individual, visits the headquarters of Wallace Corporation founder Niander Wallace. K meets Wallace's personal Replicant assistant, Luv, who is able to identify the body as Rachael, an experimental replicant. Luv lets K into the corporate archive, where K examines an old audio file of Rachael, through which he learns of her romantic ties with former veteran blade runner Rick Deckard.
K does some research on Deckard, and finds his old colleague Gaff in a retirement home. Gaff tells him that Deckard and Rachel fell in love, and eloped. K asks if Gaff knew that Deckard would one day leave society; Gaff confirms, saying that there was something in Deckard's eyes that told him he was finished hunting Replicants.
Meanwhile, Luv reports what she has learned to Wallace himself. Wallace laments that humanity has only founded less than ten off-world colonies; in order to spread out, much more Replicants will be necessary. He believes that reproduction in Replicants can bolster his production and provide the opportunity to expand his off-world operations, but lacking the technology to give them this ability himself, Wallace sends Luv to steal Rachael's remains from LAPD headquarters and follow K to find Rachael's child.
K is walking through the city's entertainment district to buy dinner, where a mysteriously cloaked woman commands three Replicant prostitutes to find out what he knows. One of them, Mariette, tries to seduce him for sex, but noticing he carries a holographic projector, she figures that he is not into "real girls," and leaves. In the meanwhile, Luv has entered the police station to retrieve Rachael's remains, coldly killing the forensic who discovers her doing it.
Returning to Morton's farm, K finds a hidden note scrawled into one of the walls. The note consists of a date that matches a childhood memory about hiding a toy horse, which he later finds at an orphanage, suggesting that his memories — which he thought were implants — are real. Joi insists this is evidence that K is in fact a real person. While searching birth records for that year, he discovers that twins were born on that day with identical DNA except for the sex chromosome; only the boy is listed as alive. K seeks out Dr. Ana Stelline, a memory designer who informs him that it is illegal to program Replicants with humans' real memories, leading K to believe he might be Rachael's son.
Greatly agitated by these thoughts, K is subjected to another a test of his Replicant behavior, and he apparently doesn't do that well. Going home, he finds Mariette in his room. Joi reassures him that this is her doing, because she needs Mariette for something. She synchronizes her holographic program with Mariette, so she is able to steer Mariette's body and make love to K this way. The next morning, K is called to the station, while Mariette leaves, but not before placing a tracking device in his coat.
K arrives at the station, and is confronted by an angered Joshi. He has failed his last test, meaning that he is at great risk of being fired from his position, which for a Replicant usually means immediate retirement. But K explains to her that he failed the test because he completed his mission in killing the child. Joshi, sympathetic towards him, believes him and tells him that she will see to that he is suspended rather than fired, which will give him 48 hours to disappear. Returning to his apartment, K starts to pack up his stuff. Joi demands to come along on his quest, and suggests that K should transfer her fully to his mobile emitter, and erase the data on her harddisk in the apartment, so what she has recorded cannot be used to tack him down. K warns her that doing so would make her "mortal," as all her programming and memories would be on the mobile emitter, and it would mean the end of her if it got seriously damaged, but Joi insists, saying that she understands the risks involved. K complies with her wish and then breaks the tracer antenna in the mobile emitter, but unbeknownst to him this triggers an alarm back in Luv's office.
K has the toy horse analyzed and finds traces of radiation that lead him to the ruins of Las Vegas, where he finds Deckard. Though skeptical and even outright hostile towards K at first, Deckard eventually comes to believe that K is just there to find out the truth as he claims, and reveals that he and Rachael indeed were lovers and had a child on the way. Deckard, however, realized the danger associated with this for the both of them, and was forced to leave the pregnant Rachael with a group of rogue Replicants working for the Replicants freedom movement to protect her, and he taught them how scramble the birth records to keep the child hidden.
Meanwhile, back at the LAPD HQ, Luv confronts Joshi in her office, demanding that she discloses K's location. Joshi, however, refuses, even as Luv threatens to kill her, and calmly accepts it when Luv makes effective of her threat. Luv then uses Joshi's equipment to trace the location of K's LAPD vehicle, and sets out with a group of Replicant henchmen to kidnap Deckard. Though K and Deckard put up a fight, Luv gets the upper hand over K and leaving him badly injured and bleeding before destroying Joi's emitter out of what can only be described as petty spite, while her henchmen knocks out Deckard and takes him away.
K is rescued by the Replicant freedom movement who was tracking him with the device Mariette planted on him, and takes him to their hideout in the desert where they patch up his injuries. He is told by their leader, Freysa, that despite appearances, even the newest Replicants has a desire for freedom inside them, and they will soon be ready to claim it, once they present the child that was born of a Replicant to the world. She then informs him that Rachael's child is a girl and thus cannot be K. K deduces that Dr. Stelline is Deckard's daughter, as she is the only one capable of creating the memory and implanting it into him. Freysa then tells K that it doesn't matter if he has not been born special, as he is still in a good position to help freeing his brothers and sisters from their enslavement. She urges him to prevent Wallace from uncovering the secrets of Replicant reproduction, as it could lead him to Rachael's daughter or to the Replicant freedom movement. She tells him to accomplish this by any means necessary, even killing Deckard if he has to.
In Los Angeles, Deckard is brought before Wallace, who suggests Rachael's feelings for him were engineered by Tyrell to test the possibility of a Replicant becoming pregnant. Wallace at first tries the softer approach, presenting Deckard with a copy of Rachael, promising that she can be his if he cooperates. Deckard still stalwartly refuses to help Wallace in any way, so instead Wallace coldly executes the Rachael copy and orders Luv escort Deckard to off-world outposts to be tortured for information.
As Luv takes Deckard to the LA space port, K intercepts them, shooting down the vehicle that transports the two so it lands at the other side of the giant dam keeping the Pacific Ocean out of Los Angeles. Landing nearby, K once again confronts Luv and gets into a serious melee with her, that leaves him with a grave injury to his side, when she attacks him with a pair of knifes. Regardless, K ends up defeating Luv as he holds her down underwater and drowns her. He then rescues Deckard, who questions what is to happen to him, as Wallace will undoubtedly be trying to seeking him out as long as he is alive get the information, and the Replicant resistance will undoubtedly do the same to prevent said information to come out. K answer that by all appearances, it will look like Deckard perished in the crash when the transport vehicle was shot down and that his body was lost in the sea, meaning that he will be safe from both Wallace and the Replicants.
K leads Deckard to Stelline's office, lamenting that his best memories belong to her. Deckard asks him why he did what he did; K answers that it was never about himself, but about her. He urges Deckard to enter the office. As Deckard cautiously enters the office and approaches an unsuspecting Stelline, K lies down on the steps outside, slowly succumbing to his wounds. He stares into the sky at the falling snow, at peace with the part he played. Inside, Anna has replicated the beautiful falling snow, Deckard approaches the glass, and as she turns around he puts his hand against the glass and smiles a peaceful smile.
