This loosely plotted coming-of-age tale follows the life of 15-year-old Laurent Chevalier as he stumbles his way over the burgeoning swell of adolescence in 1950s France. After having his first sexual experience with a prostitute and dodging the lips of a priest, Chevalier contracts a case of scarlet fever. When the fever leaves him with a heart murmur, Chevalier is placed in a sanatorium, along with his over-attentive and adulterous mother.

A self-assured businessman murders his employer, the husband of his mistress, which unintentionally provokes an ill-fated chain of events.