12-year-old Juliette, timid and awkward, hero-worships her French teacher, Madame Solenska. An enlightened teacher, full of humor and fantasy, she likes seducing her young listeners: her class is her theater and her pupils her best spectators.
Convinced that she is the teacher's pet, Juliette imagines she shares a privileged relationship with Madame Solenska. But, one day when she sneaks into her teacher's house, she sees Antoine, a particularly good-looking boy in her class, leaving the building. From then on, each of Madame Solenska's gestures and looks in Antoine's direction, each word exchanged with the teenager feeds Juliette's suspicions. Juliette tortured imagination gets carried away: for her, Madame Solenska and Antoine are having a secret love affair.