MADHOUSE

The film opens with two twin girls—one sitting in a rocking chair, rocked by the other. The girl rocking the chair stops momentarily and bashes the face of the girl in the rocking chair until she bleeds into unconsciousness.

Julia Sullivan is a young schoolteacher for deaf children living in Savannah. She has horrid memories of her childhood, which was scarred by her sadistic twin sister, Mary. At the urging of her uncle, James, a local Catholic priest, Julia visits Mary, suffering from a severe skin disease, in a mental institution. The meeting does not go well, and Mary vows to make Julia "suffer as she had suffered."

As their mutual birthday approaches, Julia learns that Mary has escaped the mental institution. Soon after, several of Julia's friends and neighbors begin to die gruesome deaths in the house she lives in — some involving a mysterious Rottweiler dog who attacks its victims, mauling them to death. One of Julia's students, Sasha Robertson Jr., is killed in a park by the Rottweiler one afternoon.

Meanwhile, Julia becomes increasingly unnerved that someone — possibly Mary — is hiding inside her large house. One evening, while being dropped off by her psychologist boyfriend, Sam Edwards, she sees a light on in the house on the second floor, but finds no one there. Helen, Julia's friend, offers to spend the night with her. In the middle of the night, she is attacked by the Rottweiler on the staircase; the dog attacks and kills her, tearing open her throat. Julia awakens the following day and finds Helen gone. Given the lack of evidence of the attack, Julia assumes she went home early. Sam visits her and tells her he is forced to take a business trip to San Francisco over Julia's upcoming birthday.

Later that same day, Father James is carrying things into the basement of Julia's home. The landlord, Amantha Beauregard, passes by and offers to help him take a large bag; he tells her he is throwing Julia a surprise birthday party. Once in the basement, Amantha realizes she has just helped James carry a corpse; he then chases her through the house and stabs her to death in the attic.

The next day, on Julia's birthday, James meets her after work, takes her to her house, and blindfolds her as a surprise. In the basement, he removes the blindfold, revealing a table seated with corpses. When she attempts to escape, Julia is confronted by Mary and is taken back into the basement to be tied up. James stabs Mary shortly thereafter. Meanwhile, Sam's taxi to the airport is stalled by a flat tire. When his speech gets ruined, he returns to the house to get a copy and is attacked by the Rottweiler. The dog attempts to break through a door, but Sam manages to kill it by driving a power drill into its head by self defense.

In the basement, Sam frees Julia, who then murders her uncle James by repeated blows with a hatchet. As Julia sits on the basement stairs, Mary briefly comes to life and attempts to strangle Julia; with her last dying breath, Mary warns that Julia "will never be free." The film ends with Julia weeping and a quote by G. B. Shaw.

Julia is trapped in her basement by her uncle James and sister Mary, but ultimately survives after Sam kills the Rottweiler, Julia kills James with a hatchet, and Mary is defeated in a final struggle.

The ending brings the film’s tangled family hatreds to a violent resolution, with Julia forced to confront and destroy both her murderous uncle and her deranged twin. The film closes the loop on the childhood trauma that has haunted Julia, but not before subjecting her to a gauntlet of betrayal, violence, and survival. The final confrontation underlines the film’s theme: sometimes, family ties are the deadliest bonds of all.