As Fernanda (Rooney Mara) enters her senior year at the sheltered New England boarding school Tanner Hall, she's faced with unexpected changes in her group of friends. When Victoria (Georgia King), a manipulative troublemaker from her childhood shows up for the fall semester she immediately begins to win over Fernanda's friends: adventurous and sexy Kate (Brie Larson), and tomboy Lucasta (Amy Ferguson), while causing tension between all the girls. Escaping from the drama at school, Fernanda begins a complicated friendship with an older family friend Gio (Tom Everett Scott). Jealous of Fernanda's exciting and dangerous relationship, Victoria plots to sabotage her plans and publicly humiliate her. Meanwhile, Lucasta struggles with newfound feelings towards another classmate, and Kate is too preoccupied with making her teachers nervous to pay attention to her classes. Flirting with adulthood, each girl realizes they need each other to get through their first grown-up decisions and the consequences they bring.