Léa moves to Montreal, leaving behind her best friend Marilou and her lover, Thomas. When entering her new school, she blunders and gets noticed for the wrong reasons. To make matters worse, she learns that Thomas has a math tutor: her enemy Sarah Beaupré! Léa wants to go back to Sainte-Marie to go to a party with Thomas, but has to be content to attend virtually. Happy with Marilou's exploits, who has finally seen Cédric, Léa nevertheless witnesses a scene that leaves her devastated.
