Bill Chrushank is a psychologist who works with convicted killers at a prison. On his way to work, he endures a horrific car crash that costs him an arm. At the hospital, Dr. Agatha Webb convinces his wife, Karen Chrushank, to sign off on an experimental transplant that could replace his missing limb. Bill wakes from the operation with a stiff, unfamiliar limb and spends weeks adjusting to it, trying to resume his duties and return to a semblance of normalcy.
As he settles back into life, Bill begins to experience disturbing visions that feel like someone else’s memories. He sees brutal acts of murder through the lens of the arm, and he occasionally loses control of the new limb. At the prison, a convict comments that the tattoo on the arm is the mark of a death-row killer, and a routine check of Bill’s fingerprints reveals a shocking truth: the arm originated from Charley Fletcher, a serial killer who had murdered twenty people. This revelation unsettles Bill and drives him to seek answers beyond conventional medicine.
Dr. Webb explains that two other patients—Remo Lacey and Mark Draper—also received limbs from the same killer. Bill visits Remo, a once-struggling artist who now thrives by selling paintings created with the transplanted arm. Remo’s art seems to mirror Bill’s visions, a detail Bill insists is because he is, in a sense, painting what the killer saw. Remo, however, is more interested in his sudden success than in the ominous implications of his purchase of a new body part, and he dismisses Bill’s warnings. Bill then tries to warn Mark, who is merely grateful to be able to walk again and urges Bill to find contentment and move forward with his life.
As Bill’s agitation grows, the violence intensifies. He demands the removal of the arm, but Webb refuses, arguing that the experiment’s success eclipses any personal discomfort. A night out with Remo and Mark turns sour when a bar fight erupts after a drunken man recognizes Bill on the news. Bill’s raw strength comes to the fore as he fights off several attackers and nearly kills one before authorities intervene.
Back at home, Mark’s legs suddenly fail again, and he calls Bill in a panic. Bill rushes to Mark’s apartment and discovers Mark dead, his legs surgically removed. He immediately informs the police and urges the detectives to check on Remo. But the case escalates when Charley Fletcher, who has somehow remained alive by way of a new body, arrives with a shocking move: he rips Remo’s arm away and hurls him out a window.
At a traffic light, Charley pulls up beside Bill and the detective, handcuffing Bill’s wrist to his own. Charley speedily drags them away, and the detective desperately chases after them, afraid Bill’s arm will be ripped off. Bill uses the detective’s firearm to break free from the handcuff just before they reach a divider that splits the road. When the detective fires, Charley escapes, and Bill continues the pursuit to save himself from becoming the next victim of Charley’s terrifying reanimated form. Charley brings his severed limbs back to the hospital, reassembling a grisly collection in a glass case that writhes with a life of its own.
Dr. Webb appears and claims that she is ready to take the arm back, but Charley intercepts, knocking Bill unconscious. Bill awakens strapped to a metal table as Webb drifts closer with a circular saw. He fights to free himself and battles Charley for possession of a shotgun. In a final bid to end the nightmare, Bill snaps Charley’s neck and then destroys the glass case, blasting Charley’s body parts with the weapon. Charley remains barely alive, aiming a gun at Bill, but ends up meeting a fatal headshot from Bill.
With the danger finally behind him, Bill sits with his wife in a quiet park. He writes in his journal that, although the arm has caused more trouble than he anticipated, Charley’s death has resolved the immediate threat. He remains grateful to both Dr. Webb and Charley for the chance to live with the transplanted arm, and he vows to move forward, carrying the memory of what he endured as a warning and a testament to the resilience of the human body.
