In an abandoned provincial school, passions run high at every turn. The sickly and weak-willed wife (Vera Clouzot) and the strong, sensitive mistress (Simone Signoret) of the cruel school director (Paul Meurisse) kill him and dump his body in the pool. When the water is drained, they discover that the body has disappeared…
At the end of the film, a caption appears begging viewers not to emulate the Devils and not to tell their friends the plot.