| Director | William Asher |
|---|
High school senior Billy Lynch lives with his protective aunt Cheryl, who has raised him since infancy after his parents died in a car accident. Billy, a gifted basketball player, is offered a chance at a scholarship to attend the University of Denver. Still, Cheryl dismisses the idea, assuming that Billy will stay with her to "contribute." At school, Billy is bullied by one of his teammates, Eddie, who is jealous of Billy's close camaraderie with their coach, Tom Landers.
On Billy's 17th birthday, Cheryl changes her mind about the scholarship and asks Billy to stop by the television repair shop to have the shop technician, Phil Brody, come by to look at their set. That night, after Phil works on their television, Cheryl makes sexual advances toward him; when he refuses, Cheryl stabs him to death with a kitchen knife, which Billy witnesses through the window. Cheryl then claims that Phil tried to rape her.
A police detective (and former Marine and Purple Heart recipient), Joe Carlson, is assigned to the case and is skeptical of Cheryl and the alleged rape attempt. After discovering that Phil Brody was gay and that he was in a same-sex relationship with Tom, he assumes that the murder is the result of a love triangle between Phil, Tom, and Billy and that Cheryl is covering for her nephew. Carlson begins questioning Billy, accusing him of being a "fag," and harasses Tom, forcing him to resign from his job at the high school. Carlson also inquires from Julia, the school newspaper photographer, about her and Billy's sexual relationship. Meanwhile, Cheryl feeds Billy drugged milk, which causes him to perform poorly at his scholarship tryout, and cleans out the attic so he can have a space in the house as an apartment. Sergeant Cook, who has been casing Cheryl's home, is suspicious of Cheryl and believes Billy is innocent.
After walking in on Billy and Julia having sex, Cheryl becomes enraged with Billy. In the attic, Billy finds a photo of Chuck, a man Cheryl claims was one of his mother's old boyfriends. Billy has Julia stop by the house to distract Cheryl so he can investigate further; locked in a box upstairs, he finds his birth certificate, which indicates that Cheryl is his mother and Chuck is his father. Meanwhile, downstairs, Cheryl strikes Julia in the head with a meat tenderizer and again drugs Billy, rendering him unconscious.
Julia awakens in a secret room in the basement and discovers Chuck's mummified corpse and his severed head in a jar of formaldehyde next to a makeshift shrine. Cheryl's neighbor, Margie, having grown suspicious, arrives to investigate the goings-on on the property and is followed into the woods behind the house by Cheryl, who kills her with a machete. Cook then enters the house in search of Julia, who has been reported missing by her mother, and is also murdered by Cheryl after discovering Julia in the basement. Cheryl chases Julia out of the house, and they both fall into a pond near the woods, where Cheryl again knocks Julia unconscious.
Billy awakens in the attic, which Cheryl has adorned with his childhood toys, and stumbles downstairs to call the police. While he is attempting to dial 911, Cheryl attacks him with a knife, and a struggle ensues, ending with Billy impaling her with a fireplace poker. Billy calls Tom, asking for help. Carlson then arrives at the house, finds Tom treating Billy's stab wounds, and sees Cheryl's corpse on the floor. Furious, Carlson blames Billy and Tom for the crimes and draws his gun on them despite Julia's cries that Cheryl is responsible. Tom and Carlson get into a scuffle, during which Billy grabs the weapon, repeatedly shooting Carlson. Carlson dies while Billy and Julia embrace, both crying.
Billy stands trial for Carlson's death but is unanimously acquitted due to "temporary insanity". Billy and Julia later attend college together.