Suzanne, a 15-year-old Parisian girl, lives with her volatile, abusive family: her furrier parents and older brother Robert, a writer. She's dating a boy named Luc, who complains about not seeing her as much as he would like. At a cafe, Suzanne mingles with sailors and an American visitor. She and the American head outdoors and have sex, though the experience leaves her miserable. She tells a friend she regrets her unfaithfulness to Luc, but she breaks up with him and becomes increasingly promiscuous. Her father is close to Suzanne but reacts with suspicion and violence when Suzanne goes on a double date with her cousin Solange. When Suzanne returns, her father expresses concern with her changing demeanor, saying she smiles less and seems increasingly bored. He also discloses he has found another woman and is planning to leave the family.Several days later, Robert tells Suzanne their father has left, and Robert assumes management of the household. Suzanne continues her affairs, though she admits she is unable to feel love. Her mother is desperately unhappy and grows increasingly frustrated with Suzanne's skimpy clothes, her letters from boys, and her attitude at home. Her brother and mother both beat Suzanne during family arguments. Luc returns to Suzanne and asks her to resume their relationship; she refuses. Miserable, Suzanne asks Robert to send her to boarding school, saying she can no longer tolerate home life and has contemplated suicide. She says she is only happy when she is with a man; Robert professes an inability to understand this.Back in Paris, Suzanne begins a more serious relationship with a young man named Jean-Pierre. While she still says she is unable to feel love, she becomes engaged. Luc reappears and begs her to cancel the wedding. Though she confesses she has considered doing that, she tells him that Jean-Pierre provides her with inner peace for the first time. At a celebratory dinner party, the father unexpectedly shows up, questioning the happiness of the family and revealing Suzanne has been visiting him. He later shows up to see Suzanne leave for her honeymoon, but with another man, leaving Jean-Pierre behind.