One night, after trying to kill herself in the ocean, teenager Jill Bradley recuperates at a hospital and recalls events leading up to her attempted suicide: On her birthday, Jill returns home expecting to spend the evening with her parents, Frank and Alice, but finds that they have left her a birthday cake and gone out. Sad and lonely, Jill takes a walk and runs into her boyfriend, Larry Lindsay, who invites her for a drive. Later, Alice and Frank, a struggling insurance salesman, come home and immediately begin arguing about money. When Jill shows up, her parents scold her for staying out late and not doing the dishes. The next day at school, Jill's chemistry teacher, Miss Druten, expresses concern about recent changes in Jill's attitude and writes her mother a note about Larry. Alice is nonplussed by the note but becomes upset when she discovers that Jill has charged a new dress to her account. Although Alice, who has just bought a hair dryer for herself, demands that Jill return the dress, Frank tells Jill she can keep the outfit if she does her chores and stays in. Jill agrees, but as she is washing the dishes, Larry shows up and persuades her to accompany him to a roadhouse. There, Larry and Jill drink and talk about their relationship until the police arrive for an impromptu inspection. To avoid arrest for selling liquor to minors, the bartender ushers the teenagers into the cellar, where they spend several hours. Later, as a tipsy Jill tries to sneak up to her bedroom, she knocks over the hair dryer, waking her parents. Smelling liquor on her breath, Frank angrily orders Jill to return the dress, which Jill had purchased for a school dance, and forbids her to attend the event. Aware that her parents will be out for the night, Jill borrows a dress from her friend, Susan Tanner, and goes to the dance anyway. Soon after arriving, Larry talks Jill into going with him to a fancy restaurant, where he lies to the waiter that Jill is his sister and that they are waiting for their parents. Larry orders ginger ale for himself and Jill, and a bottle of champagne for his "parents," then surreptiously switches the two drinks. The teenagers dance and drink until closing, then go to Larry's empty house. There, Jill and Larry kiss and confess their love for each other, and Jill talks about marriage until Larry passes out. The next day at school, Larry avoids Jill, then confesses to her that his mother found him on the couch and called Jill a tramp. Jill tries to convince Larry that only their love matters, but he ends the romance. At home, Jill tries to talk to her mother about her problems, but Alice is too busy preparing for her canasta club to offer much solace. Instead, Alice recommends that Jill forget about Larry and start seeing other boys. Jill takes her mother's advice and, although her dates are innocent, soon acquires a reputation at school. Humiliated and confused, Jill attacks one girl who insults her and is called to the principal's office. Later, after he has been summoned by the principal, Frank yells at Jill and reveals that the principal told him that she was not "nice." Frank slaps Jill, and she runs out of the house in tears. Jill then goes to Susan's house, but Susan informs her that her parents have forbidden her to see Jill. Distraught, Jill wanders off, ending up at the beach. Back in the present, Jill's doctor tells Frank and Alice about the attempted suicide before sending Jill home from the hospital. Guilt-ridden, Frank tries to throw a surprise party for his depressed daughter, but finds that none of her friends will come. Hoping to cheer Jill up, Frank takes her to the roadhouse, where the two of them win a dance contest. Jill's fun soon ends when a drunken Larry accosts her, then unaware that Frank is her father, tells him his date is "dirty." Enraged, Frank slams Larry into the bar, cracking his skull. Frank is arrested for assault and battery, but orders Jill not to say anything in his defense. Frank refuses to reveal why he hit Larry and is found guilty. As the judge is about to sentence him, Jill insists on testifying, risking her own reputation to clear her father. Convinced that Frank was provoked, the judge acquits him, and Frank tells Jill how proud he is of her. Alice finally realizes how neglectful she has been and tearfully pleads her daughter's case to Susan's parents. That night, Alice surprises both Frank and Jill when all of Jill's friends show up at their house, eager to offer their love and support.