Diabolique

A second-rate boys' boarding school in Saint-Cloud, Hauts-de-Seine, in the Paris metropolitan area, is run by the tyrannical and cruel Michel Delassalle. The school is owned, however, by Delassalle's wife Christina, a wealthy, devout Catholic immigrant from Venezuela who works there as a Spanish teacher. The frail Christina suffers from a chronic heart condition. Despite Christina's unstable health, Michel subjects her to significant emotional abuse, humiliating and mocking her, as well as mistreating the students. He also carries on an extramarital relationship with Nicole Horner, another teacher at the school, whom he physically abuses. Rather than antagonism, Christina and Nicole have a somewhat close relationship, primarily based on their apparent mutual hatred of Michel. Unable to stand his mistreatment any longer, Nicole devises a plan to murder Michel. Though hesitant at first, Christina ultimately consents to help Nicole. Using a threatened divorce to lure Michel to Nicole's apartment building in Niort, a town several hundred kilometers away, Christina sedates him with laced whiskey before the two women drown him in a bathtub. Concealing his body in a wicker trunk, the women drive back to the school, where they dump his corpse in the school's unused swimming pool. When his corpse floats to the top, they think it will appear to have been an accident. Almost everything goes according to their plans until the body fails to surface. Michel's corpse is nowhere to be found when the pool is drained. Afterwards, the suit that Michel had been wearing when they drowned him is returned from the dry cleaners. When the proprietor of the dry cleaners also returns a key to a room in a nearby hotel that was with the clothes, Christina goes to the room. There, the cleaning man tells her that Michel had kept the room for a while but was rarely if ever seen and stored nothing there. Nicole sees in the newspaper that the police have found the corpse in the Seine. However, when Christina goes to the morgue, she finds it is not actually Michel's body. There, she meets Alfred Fichet, a retired senior policeman now working as a private detective. He becomes involved in the case, much to Nicole's chagrin. Christina, Nicole and other teachers find a student who claims that Michel has ordered him to rake leaves as punishment for breaking a window. Accusing him of lying, Christina confiscates his slingshot. Under the stress, Christina's heart condition worsens, and her doctors fear she may die soon unless she maintains strict bed rest. When the school photograph is taken, the result seems to show Michel's spectral figure in the window behind the students. Unnerved, Nicole leaves the school; she asks Christina to accompany her, but she is too ill and afraid. Christina, overcome by fear, confesses everything to Alfred. He does not believe her, but he investigates the pool. That night, Christina hears noises and wanders around the school. When she realizes that someone is following her, she runs back to her room. There, she finds Michel's corpse submerged in the bathtub, which is filled with water. Michel rises from the tub, and Christina suffers a fatal heart attack. It is revealed that Michel and Nicole have set up Christina from the beginning, with Michel acting as a vengeful ghost to scare Christina to death. However, Alfred hears their celebration and exposes their plot, telling them they will be sentenced to 15 to 20 years in prison, depending on the judge. The school is closed in the wake of the scandal. As the children and teachers leave, the same boy who had earlier broken a window breaks another. When asked how he recovered his slingshot, the boy says that Christina gave it to him.

Plot from Les Diaboliques (film)CC BY-SA 4.0