At the close of the 21st century, following the devastating aftermath of World War 3, the Earth has become a hostile place with scarce habitable land. The remaining territories are split into two entities: the United Federation of Britain (UFB) and the Colony (Australia). Many inhabitants of the Colony travel to the UFB to seek work in their factories, utilizing a gravity elevator known as "the Fall" that traverses the Earth. Amidst this divided world, a Resistance emerges within the UFB, aiming to improve the bleak conditions faced by the Colony's residents.
Among the denizens is Douglas Quaid (played by Colin Farrell), a factory worker who becomes intrigued by the idea of vacationing in a fabricated reality offered by Rekall, a company that specializes in implanting artificial memories. During a consultation, Rekall employee McClane (John Cho) persuades Quaid to undergo the procedure to implant the memories of a secret agent. However, during the preliminary tests, McClane uncovers that Quaid possesses genuine memories of being a spy. In a sudden twist of fate, their session is interrupted by a SWAT team that opens fire, forcing Quaid to instinctively defend himself, resulting in the demise of the officers before he manages to escape.
Returning home, Quaid is confronted by his wife, Lori (Kate Beckinsale), who attempts to eliminate him, unveiling the shocking truth that she is not the loving partner he's known for the past seven years, but rather an undercover agent working for the UFB who has been observing him. In a desperate flight, Quaid encounters Hammond (Dylan Scott Smith), who claims to be a former ally. He communicates with Quaid through a mobile device embedded in his hand, guiding him to a safe-deposit box nearby, which Quaid ultimately cuts out of his hand to prevent being tracked. Inside the box, he finds a taped message from his previous identity, which directs him to a hidden apartment within the UFB.
While fleeing from relentless pursuers, Quaid encounters Melina (Jessica Biel), the enigmatic woman who appears in his dreams. She aids him in reaching the apartment, where he plays a piano to activate a secondary recording. This tape unveils that Quaid was initially Carl Hauser, a proficient agent under UFB Chancellor Vilos Cohaagen (Bryan Cranston), who had been tasked with infiltrating the Resistance to eliminate Mathias. However, upon meeting Melina, and realizing his misplaced loyalties, he resolves to join the Resistance instead. It is revealed that Hauser was apprehended by the UFB and had undergone memory modifications.
The recording details a nefarious scheme by Cohaagen to use the mechanical police force to invade the Colony, expanding UFB territory. Yet, Hauser had perceived a critical code capable of halting the robotic army, which can be retrieved with assistance from the Resistance leader, Mathias (Bill Nighy). Melina shares a poignant connection with Hauser, having been his lover before he was captured. During a chaotic encounter, Melina sustains a wound on her hand, leaving a scar as a haunting memory from their past.
As the police lay siege to their location, trapping Quaid and Melina, Quaid's colleague from the Colony, Harry (Bokeem Woodbine), appears, attempting to persuade him that he remains caught in a Rekall-induced fantasy. Torn between conflicting emotions, Quaid ultimately makes the heart-wrenching choice to shoot Harry.
Fleeing yet again from the relentless dangers posed by Lori, Quaid and Melina strive to reach Mathias. Just as Mathias assists in unlocking Quaid/Hauser's memories, the SWAT teams led by Lori and Cohaagen break in. Cohaagen reveals a devastating betrayal—that Quaid/Hauser had been unwittingly working for him, with his defecting allegiance being planted by Cohaagen himself. In a shocking act, Cohaagen kills Mathias and orders the reprogramming of Hauser's mind, intending to regain his control. Cohaagen and Lori then abduct Melina, just before the enigmatic Hammond, posing as a SWAT member, orchestrates an escape for Quaid at the cost of his own life.
Cohaagen launches a massive assault on the Colony using the Fall. Ingenious and determined, Quaid sneaks onto the Fall, planting detonators while searching for Melina. Once reunited, they ascend to the top of the Fall as it descends toward the Colony. In an epic showdown, Quaid battles against the soldiers and the ever-menacing Cohaagen. When Quaid’s explosives detonate, they leap from the Fall, narrowly escaping its plunge into the depths below, engulfing Cohaagen and his forces.
In a disorienting awakening aboard an ambulance, Quaid is greeted by Melina, only to discover she is, in truth, Lori disguised. This revelation forces a climactic confrontation where Quaid fights and ultimately kills Lori, gaining his freedom. He and Melina finally reunite, as a Rekall advertisement buzzes in the background, leaving them uncertain of their reality but together in their fight for survival.
