Henri-Georges Clouzot's taut, hair-trigger suspense thriller features Simone Signoret and Charles Vanel in two classic screen performances. At the end of the film, Clouzot begs the audience, "Please do not reveal the ending to those who have not yet seen the film!" So what follows is just the set-up. The film takes place at a French boys' boarding school run by headmaster Michel Delasalle (Paul Meurisse), who is hated not only by his students but by also by his wife Christina (Vera Clouzot) and mistress Nicole (Simone Signoret). Michel has a propensity for beating the women in his life; Nicole first appears wearing sunglasses to hide a black eye she received from him. Nicole speaks to Christina about a plan to murder Michel: Nicole will convince Michel to come to her home in a distant village, where he will then be drowned in a bathtub. Returning to the school, his body will be dumped into a swimming pool and it will look like an accident or a suicide. The two women succeed with the murder and throw the corpse into the pool. But then the body disappears from the pool and the mystery begins. Arriving on the scene is the rumpled police inspector Fichet (Charles Vanel), who investigates the disappearance of Michel and comes to some startling conclusions.