Anne de Boissy and Lore Fournier are two adolescent Angevin girls who stay at a Catholic boarding school. Both have affluent and conservative families living in the countryside and on becoming friends and later lovers, the two decide to join forces in their malicious rebellion. When Anne’s parents take a long trip and leave Anne behind during summer vacation, Lore starts to stay with Anne at her château. They play some malicious games on two men: releasing the cows of the cowsherd Émile as well as setting fire to his home, and killing the pet birds of the mentally challenged gardener Léon. They store sacramental bread from church and prepare the abandoned chapel at the château for a mock marriage ceremony in which they dedicate themselves to Satan. One night, they meet a motorist who ran out of gasoline and invite him to the château. The girls seduce the man and when he attempts to rape Lore, he is killed by Anne. When a detective is sent and he finds clues linking them to the murder, the pair is convinced that the man’s body will be discovered and immolate themselves at a recital while reading poems by Baudelaire.