DEMENTED

Linda Rodgers suffers a violent gang rape at her California ranch which leads to her becoming temporarily institutionalized. She is eventually released to the care of her physician husband, Matt, while her rapists are sentenced to prison terms.

Linda struggles to assimilate back into normal life, tormented by visions of multiple men donning Halloween masks infiltrating the home and attacking her. Meanwhile, Matt carries on an affair with his mistress, Carol, neglecting to emotionally tend to Linda. To evade her suspicions about his absences, Matt claims to be working night shifts at the hospital. After Linda experiences an apparent home invasion while home alone night, Matt finds her distraught. He phones the police to investigate, but they find no evidence to support her claims.

Linda's sister Annie arrives to visit her, despite Linda's insistence that she be left alone to process her trauma. Following an argument at dinner, Annie leaves. Linda's psychiatrist Dr. Dillman, while making a house visit, finds her neighbor Mark peering through a window and assumes him to be an intruder, but Mark insists he was only checking on Linda, which she believes to be true.

After Dr. Dillman leaves, Linda is attacked by a masked man in her bed, whom she kills with a meat cleaver. The incident results in Linda entering a psychotic state. Three other male attackers—revealed to be local young men who have been playing a cruel prank on Linda—loiter downstairs. Dressing herself in lingerie, Linda confronts one of the attackers, disarming him and causing him to unmask himself before offering him a spiked glass of wine, which causes him to lose consciousness. Police officers scheduled to make a nightly visit to the house arrive, but leave the property, assuming Linda has gone to stay with a friend as the house is entirely dark.

Linda finds a third male assailant in a downstairs bedroom, and begins to seduce him before castrating him with a piano wire and hacking him to death with the cleaver. She proceeds to kill a fourth assailant while he is peering through the home's kitchen window. The male prankster whom Linda previously poisoned regains consciousness, bound and gagged at the dining room table. Linda prepares a dinner for the two, ranting and raving incoherently, accusing him and his friends of being her rapists. He attempts to reason with her, claiming Mark put them up to the prank, before killing him with a shotgun.

Matt returns home, preparing to finally admit his affair to Linda. In their bedroom, he removes a sheet, revealing the bloodied body of one of the pranksters, before Linda maniacally lunges at him with the cleaver.

Linda kills the masked intruders in a violent spree and ultimately attacks her unfaithful husband upon his return.

The ending of Demented cements its status as a bleak rape-revenge tale, with Linda’s trauma spiraling into a violent psychosis. Her retaliation against the intruders and her final attack on Matt reflect both her inability to find safety and the destructive impact of neglect and abuse. The film closes on a note of chaos, suggesting that the cycle of violence and mistrust has fully consumed her.