THE YOUNG, THE EVIL AND THE SAVAGE

A woman is drowned in a bathtub and then placed in a trunk that lands in a pickup truck going to St. Hilda College. Among the teachers is a newcomer, Mrs. Clay, a science teacher. In addition, there is a young teacher, Richard Barrett, a diving instructor, and the college gardener La Foret. There are only seven girls at the institute, as the others are on vacation. Arrived at the destination, the trunk is brought to the basement.

Soon one of the girls, Betty Ann, who had gone to the basement, is strangled and taken away. The search for the missing girl begins. Jill claims Betty Ann is dead and was killed by the gardener. The girls are told not to leave their rooms, but one, Lucille, has an appointment with her teacher Richard, with whom she has been carrying on an affair. Lucille defies the lockdown and goes to a small house on a hill, where she discovers Betty Ann's body and runs away. She meets Richard and tells him everything. When they return, Betty Ann's body is gone. Lucille is desperate to leave school, so Richard advises her to pack and wait for him at the pool.

Lucille returns to boarding school, and while she takes a shower, the gardener spies on her from a tree. She notices strange movements on the plant and returns to the room frightened. Another girl, Cynthia, takes a shower and is killed in front of the gardener. Jill finds the body, and the police are called. Shortly after the agents arrive, the gardener is killed. Lucille wants to escape because she believes Cynthia was accidentally killed in her place. Meanwhile, she entrusts herself to a classmate, Denise, and tells her about the date with Richard at the pool. As she has to be questioned by the police, she asks her friend to go to her place. Denise accepts and is attacked by the killer, but Jill, who has followed her, intervenes, though the attacker escapes. The police dogs finally find the body of Betty Ann.

Through the course of investigation, it is discovered Lucille comes from an affluent family, and is due to inherit a large windfall on her birthday, which is the next day. She has been trying to contact a relative who has been administering her trust in the meantime, but cannot reach them. Lucille has another encounter with Richard near a lime pond, which is interrupted by Mrs. Clay, and they leave. Shortly after, the body of Mrs. Clay has been found in the lime pool by police.

Lucille is determined to leave the school with Richard. She finds him standing in the window of his quarters, but when she enters and calls to him, Richard's unconscious body is pushed down the stairs. The killer reveals himself: it is Pierre, Lucille's cousin, who has been disguising himself as Mrs. Clay at the school. He has been spending Lucille's inheritance, and has set to kill her to capture the remainder of the money, and blame it on the real Mrs. Clay, whom he earlier murdered and shipped to the school in the trunk, using the body to stage her death as a suicide.

Pierre wounds Richard, but Inspector Durand kills him. Tranquility returns to college, and Lucille and Richard end up together.

The killer is revealed as Pierre, Lucille's cousin, who had been disguising himself as Mrs. Clay to gain access to Lucille's inheritance. Pierre is confronted after attacking Lucille and Richard, exposing his scheme and ending his spree.

The climax resolves the central mystery by unmasking Pierre, whose impersonation and manipulation allowed him to orchestrate the murders and attempt to secure Lucille's fortune. His exposure brings closure to the terror at St. Hilda College, restoring a sense of safety to the surviving characters and tying up the film’s intricate web of deceit and betrayal.