The film begins with Simon Newton (James McAvoy) recounting the history of art auctions as prime targets for thieves, and how security measures continuously adapt in response. Yet, as Simon reflects, so too do the criminals. We are introduced to Franck (Vincent Cassel), who stealthily surveys Delancy's auction house, where Simon is employed. In a dramatic turn of events, Franck's crew executes a daring theft of a Goya painting. Despite Simon's efforts to thwart the crime by adhering to established protocols, he is overpowered and knocked unconscious, allowing the thieves to escape. To his dismay, Simon soon discovers that the painting is missing from the frame!
In the aftermath, Simon gains the public's admiration and is discharged from the hospital. However, he arrives home to find both his house and car ransacked. Franck soon confronts Simon, demanding to know the painting's whereabouts. Sadly, Simon suffers from mild amnesia due to his head injury, leaving him clueless about the theft. As suspicions rise, he is believed to be the inside man, and Franck's team resorts to torture in hopes of extracting the truth. In an unconventional turn, Franck decides to employ Dr. Elizabeth Lamb (Rosario Dawson) for hypnotherapy sessions to unlock Simon's memory.
Posing as Mr. Maxwell, Simon visits Elizabeth, feeling ill at ease with his fabricated identity. Elizabeth skillfully eases his discomfort. In a light trance, Simon manages to retrieve his lost car keys, but when he edges closer to recalling the painting, Franck intervenes, steering him off course. Intrigued, Elizabeth conducts her research on Simon, uncovering details about the heist and returning to renew their session. She cleverly plays a recording and subtly queries Simon about Franck without his awareness. Recognizing her knowledge of Franck, she strikes an arrangement with him, proposing to share in the heist's spoils.
During another session, Simon is once more placed into a trance, with Franck and his crew present. As he nears a breakthrough, traumatic memories disrupt his recollection. He confesses his gambling addiction and explains that the robbery was an attempt to pay off debts. Elizabeth reassures the gang that Simon believes they will kill him and suggests they should show him their vulnerable side. She informs Franck that susceptible subjects can be manipulated under hypnosis.
In a subsequent session, Elizabeth again hypnotizes Simon, and he begins recounting the heist, believing he smuggled the painting away before being hit by a car driven by Elizabeth. Upon awakening, he recalls an MRI session where Elizabeth urged him to avoid fixating on her. Elizabeth discusses her findings with Franck, leading them to understand Simon's infatuation with her may be obstructing his memory of the painting. She controversially proposes a sexual encounter with him, prompting tension between her and Franck, culminating in a brief passionate interlude.
The following day, Simon discovers startling plans for the gang to eliminate him, leading him to reach out to Elizabeth for guidance. She directs him to Franck’s bedroom, where he retrieves a gun and reveals the painting's whereabouts before unexpectedly shooting the gang. However, he awakens in Elizabeth's room, realizing the violence transpired in a trance state. In a split of allegiance, Elizabeth escapes with Simon's car, only for Franck to confront him, asserting that Elizabeth has been manipulating them all along. Their mutual conflicts come to a head as the gang resorts to torturing her for information, while Simon ultimately reveals the painting's location.
As tensions escalate, Elizabeth shares a final kiss with Simon, discreetly passing him something in her mouth. Franck and Simon retreat downstairs, where the gang's sinister intentions toward Elizabeth become evident. In a twist of fate, Simon, having regained control, retaliates against the gang members using the gun. However, he hesitates when it comes to Franck's life, sparking further turmoil.
The trio finally retreads the chaotic events by visiting the car park where they recover the vehicle involved in the initial hit-and-run. Driven by desperation, Simon forces Elizabeth to help him access his suppressed memories. They travel back in time to when Simon first met Elizabeth, aiming to rid himself of his gambling issues. An affair ignites between them, drawing Elizabeth into a change as drastic as shaving herself to resemble a painting. However, jealousy consumes Simon, leading to an explosion of violence that sees him strike Elizabeth. In a move to protect herself, she uses hypnotic suggestions to erase his memories of her.
After being struck by the car during the heist, Simon's fragmented memories linger, causing him to mistakenly associate Elizabeth with the driver. Their journey leads them to an abandoned warehouse where a shocking reveal awaits: the woman Simon mistakenly killed is found in the trunk, alongside the coveted painting. He offers the painting to Elizabeth, igniting a destructive blaze that engulfs Franck. In a heart-stopping moment, Elizabeth commandeers a truck, crashing it into Simon and the flames, plunging them both into a lake.
While Franck narrowly escapes the fiery chaos, Elizabeth severs their ties. Months later, she sends Franck a cryptic video of herself with the painting, revealing her manipulation—she implanted a suggestion for Simon to reclaim the painting for her. As the closing scenes unfold, Elizabeth offers Franck a choice that determines his fate, leaving a haunting ambiguity lingering in the air as he grapples with his options, unsure of what path to take.
