Plot
Karen Nichols is a recovering alcoholic who is plagued by strange visions that may be psychic in origin. After being released from a hospital, Karen and her businessman husband Alan relocate from San Diego to a home in the Los Angeles hills. Just after moving in, Karen meets her neighbor, Madge Harper, a talkative middle-aged woman who resides across the street with her husband, Henry. She also meets Benny, a developmentally-disabled landscaper who manicures the yards in the neighborhood.
When Alan invites his boss and his boss's wife for dinner, Karen is disturbed by visions of a severed hand in her bedroom and a cloaked figure on the staircase. Unnerved, Karen attends an Alcoholics Anonymous meeting, but is again plagued by visions and flees. Karen nearly relapses in a bar, but is stopped by Larry Craig, a retired police sergeant who investigated a brutal axe murder that occurred in Karen's house one year earlier. The victim, Lucy Duncan, was a doppelgänger for Karen who was apparently murdered by her jealous son. Larry recounts to Karen that he also experienced strange occurrences in the home, and that Lucy's severed head was never located.
Larry returns Karen to her house, where she insists he tell the story to Alan. A hostile Alan chastises Karen and disregards Larry as a con artist. When Karen later questions Madge about Lucy Duncan, Madge suggests that Larry was having an affair with her, and became obsessed with the case after she died, frequently loitering in the neighborhood. His obsessive actions resulted in him being fired from the police force, and he was also a suspect in the murder. Later, Lucy's beloved cat, who has roamed the neighborhood since her murder, enters the house and flees into a crawlspace. While attempting to find the cat, Karen and Benny discover Lucy's severed head beneath a crawlspace entry in a closet.
Karen accompanies Larry to a psychiatric hospital to visit Lucy's son Edward, after which Larry admits to Karen that Edward may be his biological son. That night, Karen returns home and finds Alan drunk, angered over having been fired from his job. Alan attacks Karen, questioning her whereabouts, before fleeing. Outside, Madge approaches Karen, who rebuffs her. In the house, Karen begins to drink from Alan's whiskey bottle.
The next day, Larry confronts Benny, who has been drinking all day a bar, accusing him of Lucy's murder. While attacking Benny, Larry experiences a psychic vision that he realizes is a premonition, and flees to Karen's house. There, Karen, drunk, also begins experiencing visions, while a cloaked figure with an axe breaks into the house. When Karen finds Lucy's cat murdered in the bathroom, the assailant attacks her, and is revealed to be Madge. During the chase, Larry arrives, and Madge falls from a window and is seriously injured.
Later, at the hospital, a psychiatrist explains to Alan and Larry that Madge's murder of Lucy and attempted murder of Karen were driven by her irrational fears that her husband was being unfaithful to her with the neighborhood women. In another room, Karen, driven mad, laughs maniacally in a straight jacket.
