Laurent, a precocious and sexually curious 15-year-old boy from a bourgeois family in 1954 Dijon, is sent to a spa resort to recover from a heart murmur caused by scarlet fever — accompanied by his beautiful, free-spirited, and emotionally immature mother Clara, with whom he shares an unusually close and flirtatious bond. At the resort, while his father is away and his older brothers are occupied with their own pursuits, Laurent loses his virginity to a girl his age — but on the final night, after Clara returns drunk and heartbroken from discovering her own lover has abandoned her, she and Laurent end up sleeping together in a moment that is portrayed not as trauma but as tender and almost inevitable, given the peculiar intimacy they have always shared.