Young Michel is in love with the attractive Madeleine, so he decides to tell his parents of his intention to marry her. He thinks his announcement is innocent enough; his engagement, however, threatens to reveal dark secrets lurking within his family's home. Yvonne, Michel's overbearing mother, concocts an elaborate scheme to drive Madeleine away, thus keeping uncomfortable household truths from being exposed.
A village in the French Alps is rocked by a series of crimes, including the theft of a sacred ring and the murder of a man dressed as Père Noël (Father Christmas).
Loursat, a lawyer, lives with his daughter Nicole in a sinister and vast bourgeois residence. Abandoned for nearly twenty years by his wife, the brilliant lawyer has sunk into alcoholism and his relationship with his daughter is virtually non-existent. However, one day the corpse of a stranger is discovered in the residence of Loursat. Nicole, who frequents a gang of young people who escape boredom by stealing cars and other objects, is immediately suspected.
