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. As France is nearing the end of the first Indochina War, an open-minded teenage boy finds himself torn between a rebellious urge to discover love, and the ever-present, almost dominating affection of his beloved mother.