The film begins with an intense sequence showcasing Trevor Reznik (Christian Bale) wrestling with a heavy object. As he drives his truck near a dam, it becomes apparent that he has a body wrapped in a carpet, stirring panic within him when he notices someone approaching with a flashlight. In a moment of sheer terror, he pushes the carpet aside, causing it to begin unrolling just as the stranger, asking, “Who are you?” closes in on him.
In a later scene, Trevor is seen in the bathroom, scrubbing his hands with bleach, staring into the mirror at his emaciated reflection. Stuck on the mirror is a post-it note echoing the earlier question, “Who Are You?” His life is intertwined with Stevie (Jennifer Jason Leigh), a call-girl, and after a brief romantic encounter, she jokingly mocks his alarming weight. Displaying unsettling behavior, he contorts his body to highlight his skeletal frame before slipping out of her apartment, leaving a tip behind.
Later, he shows up at his job as a machinist, where tensions run high with his foreman Tucker for his adherence to OSHA regulations—something they often disregard. In the locker room, his co-worker Jones (Reg E. Cathey) invites him for a game of cards, but Trevor’s isolation becomes clear when Jones notes his change in social habits.
The narrative progresses as Trevor frequents an airport diner where he engages in conversation with waitress Marie (Aitana Sánchez-Gijón). She inquires about his late-night visits, suggesting he might be running from something. Her concerns about his frail appearance mirror those of Stevie—“if you were any thinner, you wouldn't exist.” Amidst these interactions, he candidly confides to Stevie about his year-long insomnia.
A turning point occurs when Trevor is approached by a stocky man named Ivan (John Sharian), who claims to be a replacement at work for Trevor’s friend Reynolds. In a harrowing scene, an accident unfolds while they are fixing machinery, resulting in Miller (Michael Ironside) suffering a grave injury. Although Trevor tries to explain to his boss that he was distracted by Ivan, his boss reveals a shocking truth: no one named Ivan is employed there.
As paranoia takes hold, Trevor attempts to track down Ivan, leading to a series of unsettling events including confronting his coworkers and discovering cryptic post-it notes resembling a hangman game on his fridge. Each new blank and cryptic clue intensifies his descent into madness as he grapples with his own identity.
On Mother’s Day, he spends time with Marie and her son Nicholas (Mathew Romero Moore) at an amusement park. A traumatic incident on a ride leads Nicholas to a seizure, compounding Trevor’s guilt and anxiety as he recalls the eerie déjà vu with the hangman puzzle connecting to his mother and Marie.
As the plot unfolds, Trevor’s increasingly erratic behavior leads to conflict with his coworkers and personal relationships – notably when Stevie expresses her desire to quit her job and build a life with him, a notion that sends Trevor into further disarray. The cumulative stress drives him to confront Ivan, culminating in physical violence and a desperate quest for truth.
The repeated cycle of violence and madness brings Trevor back to his beginning, desperately trying to dispose of what he believes to be Ivan’s body, only to realize the horrifying truth behind his actions—an act of guilt that birthed his tormentor.
Fighting to piece together his fractured psyche alongside the haunting post-it note—“Who are you?”—he recalls a tragic past: the moment he distracted while driving, ultimately leading to Nicholas's death. This revelation, compressed by guilt and despair, compels him to confront reality and turn himself into the authorities, yearning for peace and closure.
As he seeks solace in a police station, declaring his intent to report a hit and run, Trevor finally finds a glimmer of rest in imprisonment, culminating in a poignant reflection of his harrowing journey. The film closes with a haunting image—the light fading to white as he drifts into comparative calm, painfully aware of the monstrous consequences of his fractured identity.
