A young, disheveled-looking man is awakened on the side of a road by passing traffic. He walks to a nearby lake and attempts to drown himself by filling his clothing with rocks and walking into the water, but is pulled out and taken to a nearby mental hospital for treatment. He is suffering from retrograde amnesia, unable to remember his name or details of his personal life, other that he lives in a house within several miles and has no father to speak of. Without any form of identification, the patient is designated “John Doe #83”, and placed under the care of psychiatrist Dr. Gail Farmer. Almost immediately, John begins to display odd behavior, with a fellow patient nicknamed “The Messiah” suddenly developing a delusion that he intends to behead him.
At her home later that night, Gail hears a window being broken and witnesses John entering her house and stealing a necklace from her nightstand. When she calls the police, they can find no evidence of a break-in, and her colleagues at the hospital tell her that John is fast asleep in his dormitory. Farmer quickly suspects that John is not all that he seems, as she continues to have strange visions while he is asleep. She theorizes to her boss Dr. Denman that John has some form of telepathy, wherein he “sends” his dreams into the minds of other people, causing them to experience semi-corporeal sensory hallucinations for the duration of the dream. Denman dismisses Gail's hypothesis as her developing a maternal bond with the young patient, and plans to have him treated with electroshock therapy against her wishes. Meanwhile, both Gail and John are haunted by the presence of a middle-aged woman named Jerolyn, apparently John's mother, who tells Gail that she must release John for everyone's well-being but disappears before she can be questioned further.
After John attempts suicide a second time, he's taken in by Denman for electroshock therapy. The moment the current is activated, John unconsciously sends violent and destructive hallucinations towards everyone in the hospital, both staff and patients. Gail rushes in and removes the electrodes. Now believing her hypothesis, Denman begins intensive study of John, while Gail continues to see Jerolyn and other cryptic visions sent by John, including one in which he lies dead with his body covered in rats. She suspects that the visions are memories of the recent past, repressed into the subconscious due to trauma. After John tells her that his mother used to lock him up in the house, she theorizes that Jerolyn, who believed that her son was a miraculous virgin birth, kept him trapped inside her house for his entire life, eventually trying to kill him with carbon monoxide poisoning when she believed he'd leave her.
John's telepathy quickly becomes more and more uncontrollable, especially after he begins “sending” while conscious. Despite Gail's protestations, John is taken into the surgical ward to have an intracranial operation to identify and neutralize the receptors causing his powers. Before the operation begins, the local Sheriff arrives to tell Denman and Gail that they found John's house and mother, but that she's been dead of carbon monoxide poisoning for five days, indicating that he killed her and not the other way around. John's placed under guard, but the moment the surgeons pierce his skull with a drill he suddenly lashes out again, this time causing the room to explode into flames. In the chaos, John steals Gail's car keys and escapes, guided by a vision of his mother.
When they arrive at their house, he turns on the gas stove to kill a swarm of cockroaches, but as he lies in bed he suddenly realizes that his mother is trying to kill him and snaps out of his hallucination. Gail bursts in and drags a suffocating John away, as they're pursued by the projection of his Jerolyn. They manage to get out of the house just before the gas ignites, destroying the house.
Some time later, John has regained his memory and tells his story – his mother tried to kill him, and when he realized what was happening, he fought her and inadvertently knocked her unconscious, leaving her to suffocate while fleeing the house. Unable to cope with what he'd done, his id took the form of a projection of his mother, trying to compel him to kill himself on multiple occasions. Seemingly cured, he leaves the hospital as Gail looks on, only to enter his truck with his mother sitting next to him, indicating he's still suffering from his condition and is bound to relapse.
