In 1985 Mexico City, a desperate Heinrich Treadway, portrayed by Dylan O'Brien, finds himself on the run from both the authorities and a formidable adversary named Bathurst, played by Rupert Friend. Joined by his accomplices, Abel (Tom Hughes) and Leona (Joana Ribeiro), they discuss a mysterious object known as "the Egg," which Treadway had stolen from Bathurst. Just before a catastrophic encounter, Treadway warns Abel to remember to "look inside" should he not survive the ordeal. In a daring escape, he leaps from a vehicle off a bridge, but his escape is thwarted as Bathurst arrives and fatally takes his companions.
Fast forward to 2020, we meet Evan McCauley, a character brought to life by Mark Wahlberg, who struggles with schizophrenia due to a troubled past filled with institutionalization and violent incidents. In dire need of medication, Evan resorts to forging a Katana for a local gangster, despite lacking any formal training in blacksmithing. After a tumultuous exchange where things spiral out of control, he finds himself in police custody, where he encounters Bathurst, now portrayed by Chiwetel Ejiofor, who ominously refers to him as Treadway, insisting they share an ancient bond.
As Bathurst attempts to jog Evan's memory about their past lives, chaos erupts when a car crashes into their location. Evan is rescued by Nora Brightman, played by Sophie Cookson, who navigates a thrilling car chase to evade Bathurst. She introduces Evan to a faction she belongs to, where Bryan Porter, played by Toby Jones, serves as the Director of Operations, aiding in their mission.
In this world, approximately 500 individuals can recall their past lives, categorized into two opposing groups: the Believers and Nihilists. The Believers, including Nora, see this gift as a higher calling to improve humanity, while the Nihilists, like Bathurst, view it as a curse, believing they are condemned to witness the apocalypse repeatedly. Unbeknownst to Evan, he is believed to be the reincarnation of Treadway, essential in locating the Egg— a device designed to annihilate all life on Earth by targeting DNA, thus halting the cycle of reincarnation.
With time running out, the Believers aim to awaken Evan's memories to secure the Egg before Bathurst uses brutal methods to extract the secrets from him. Nora reveals to Evan that individuals start remembering their pasts at a young age, a phenomenon that led to his schizophrenia diagnosis. Meanwhile, Bathurst discovers Bryan's whereabouts in New York City and brutally kills him, stealing vital information that leads him closer to Evan.
Despite the escalating threat, Evan struggles to unlock Treadway's buried memories, a puzzle complicated by a traumatic brain injury. In a bid for help, Nora takes him to the Artisan's lair, where Jason Mantzoukas assists in his recovery. After a session in the Artisan's machine, Evan finally begins to uncover haunting memories of his past life, revealing the shocking truth—Treadway was murdered not long after Abel and Leona, and his body was hidden by the Believers.
Bathurst, now aware of the hidden Egg inside Treadway's former body, embarks on a mission to retrieve it. A fierce clash occurs at the Artisan's facility, leading to a daring escape by Evan and Nora. However, the stakes rise even further as Bathurst secures Treadway's remains, unleashing chaos as he prepares to deploy the deadly Egg.
As both factions gear up for a final showdown, Evan joins Nora in an assault on Bathurst’s stronghold. In a climactic confrontation high above the world, Bathurst shoots Evan, yet the steel plate in Evan's skull provides him with a chance to retaliate. The ensuing aerial battle culminates in Evan successfully stopping the Egg’s activation just in time, sealing Bathurst's fate as he makes the ultimate sacrifice, drowning with the Egg in the ocean.
In the aftermath, while Nora and the Artisan liberate the trapped souls of the Believers, years later, as fate would have it, Nora and Abel are reincarnated, destined to meet once more. Meanwhile, Evan's rebirth in Jakarta, Indonesia marks a new beginning; he is approached by the elder Artisan, who offers him a Katana, prompting Evan to regain fragments of his former life. The cycle of life continues, intertwining their fates in an unending story of reincarnation.
