Laurent Chevalier, a 14-year-old boy living in Dijon in 1954, loves jazz, consistently earns the highest grades in his class, and openly opposes the First Indochina War. His home life is a blend of affection and distance: his father, Charles, is a hardworking gynecologist who rarely shows warmth, while his mother, Clara, is tender and warm despite the complexities of their family. He has two older brothers, Thomas and Marc, who are pranksters by heart, which contrasts with Laurent’s quieter passions. As he moves through adolescence, Laurent grapples with taboos, including moments of shoplifting and masturbation, highlighting the tension between curiosity and propriety that threads through his teenage years. The unsettling discovery that Clara has a lover further jars the family balance; when Laurent goes to tell his father, Charles is preoccupied with his patients and responds with anger, abruptly cutting the moment short.
One night, Thomas and Marc take Laurent to a brothel, where he experiences sex with a prostitute named Freda. The moment is interrupted by the brothers’ drunken exuberance, leaving Laurent shaken and unsure about what he has just learned about desire and boundaries.
The arc of Laurent’s adolescence continues when he joins a scouting camp and contracts scarlet fever, which leads to a heart murmur. He is bedridden for a month, and Clara, along with their loyal maid Augusta, takes care of him during his illness. A teacher at his Catholic school remarks that the illness has somehow matured him and notes that Laurent has made progress in his studies, urging Clara to treat him with a greater sense of adulthood and responsibility.
As Laurent’s illness requires ongoing treatment, he and Clara check into a hotel near a sanatorium. An error by Charles’s secretary Solange results in both of them being booked into a single room, and with the hotel at capacity, there is no extra room available. In this confined space, Laurent becomes fascinated by two young girls, Hélène and Daphne, and his curiosity extends to observing his mother from a distance as she bathes. He makes advances toward Hélène, but she tells him she is not ready for sex, and he accuses her of being a lesbian. Clara, meanwhile, leaves briefly with her lover but returns later, distressed by their break-up, and Laurent offers her comfort.
After Bastille Day, a night of heavy drinking leads to a disturbing turn as Laurent and his mother have sex. Clara tells him afterward that this incest will not be repeated, but she also says that they should not regret what happened. Laurent leaves their room, and after a failed attempt to seduce Hélène, he spends the night with Daphne. When morning comes, the family senses what has occurred, and, in a moment that catches them all by surprise, they share a hearty laugh together, a sign of their complicated, unspoken bonds and the strange, dark humor that laces through their days.
