Psychiatrist Dr. Miranda Grey (Halle Berry) has her life turned upside down after a traumatic car accident during a stormy night. In her desperate attempt to assist a girl she encounters on the road, Miranda reaches out only to discover that this girl, who initially seemed like a victim, is actually a ghost. This sinister spirit possesses Miranda, leading to a hazy loss of consciousness and a shocking awakening in the very mental hospital where she works. Now a patient, treated by her colleague Dr. Pete Graham (Robert Downey Jr.), Miranda finds herself struggling with confusion and despair as she grapples with the grim realization that her husband Douglas (Charles S. Dutton) has been brutally murdered—and she is the prime suspect.
As she navigates her new life confined within the hospital’s walls, the ghost begins to manipulate her body, leaving messages such as the chilling phrase "not alone" carved into her skin, leading others to mistakenly believe she's self-harming and suicidal. During her stay, she forges a connection with fellow patient Chloe Sava (Penélope Cruz), who had repeatedly claimed to be a victim of abuse in the same hospital. Initially dismissing Chloe’s terrifying allegations as mere fabrications of a troubled mind, Miranda's perspective shifts dramatically when she witnesses the horrifying truth: a man attacking Chloe while leaving a lasting impression of dread.
Miranda's memories of that fateful night slowly resurface, revealing a haunting conclusion: the ghost had used her body to murder her husband. Desperate for answers, Miranda breaks free from the hospital, determined to piece together the mystery behind her actions. Her investigation leads her to a remote farmhouse in Willow Creek, Rhode Island, where she uncovers a chilling room filled with evidence of past atrocities, including a blood-stained bed and disturbing tapes that suggest Douglas was deeply involved in dark deeds. The tension escalates when the police converge on her, leading to a fateful confrontation with Sheriff Ryan (John Carroll Lynch), a man whose sinister intentions are exposed when Miranda realizes he matches her psychological profile of the real culprit.
In a harrowing struggle for survival, with the assistance of the ghost, Miranda's self-defense culminates in a tragic encounter, revealing the sheriff's own murderous nature. After reclaiming her freedom, Miranda embarks on a journey of healing alongside Chloe, reflecting on how they both aided one another in overcoming the trauma of their pasts. Yet, as she walks away, a sinister reminder of the boy she saw earlier appears—a haunting poster with the words "Have you seen Tim?" ominously taped to a pole, leaving her to ponder the lingering shadows of the past and the spectral figures that seem forever tethered to her fate.
