In 1954, Cécile, a Parisian high school student, spends the summer of her seventeenth birthday in a villa with her father Raymond, a widower, and Elsa, his mistress. Cécile and her father have a close relationship, carefree and full of pleasure. The atmosphere changes when Raymond announces the arrival of a friend, Anne. Different from Elsa and Cécile, Anne is a strict and moralizing woman. She appreciates culture, good manners, and intelligence. As soon as she arrives, a subtle conflict begins between the three women. Elsa tries to maintain her relationship with Raymond, who is also attracted to Anne. As for Cécile, she fears losing the complicity that binds her to her father, as well as their freedoms. How can she avert the threat? In the burning heat of the summer, a cruel game is being prepared with tragic consequences. A remarkable adaptation of the classic bestseller by Françoise Sagan which shocked a generation.