For refusing to squeal on her delinquent boyfriend, a teen girl is thrown into reform school where she ends up meeting his ex-girlfriend and the jealous tempers fly.

Seventeen-year-old Donna Price has been reared by her mother's sister Rita and Rita's lecherous husband, Aleck Horvath, for the five years since the death of her mother. One night, Donna's boyfriend, Gary, arrives with two new friends, Vince and Josie, and interrupts Horvath's attempted rape of Donna. After Vince beats up Horvath, the four leave in a convertible, which, unknown to Donna, Vince has just stolen. When Gary and Josie object to Vince's suggestion that they crash a party, Vince ejects them from the car and drives on with Donna to a secluded area where he starts necking with her. Reminding him that they have only just met, Donna tells him she does not want to be rushed, and asks to be taken home. On their way back, a police patrol car spots the stolen vehicle and pursues it. Vince speeds through a stop sign and runs over a man crossing the road, killing him. After Vince runs away leaving Donna in the car, the police arrest her and, later, she appears in juvenile court, where Horvath tells her that Vince has warned that if Donna implicates him in any way, he will kill her. When Donna then refuses to name the car's driver, a judge places her in the custody of the state Youth Authority's Hastings School for Girls. At the school, Donna's probation officer introduces her to superintendent Mrs. Trimble and David Lindsay, a new teacher, who is completing a thesis on juvenile psychology and expresses an interest in Donna's background. The other girls at the school are hardened offenders and attempt to ostracize her. Meanwhile, Vince is worried that Donna may still inform on him and decides to arrange for Josie to be sentenced to the institution to silence Donna. When David talks with Donna about her life and tells her that she can make good because she is intelligent and pretty, Donna thinks that he is making a pass at her. Trimble becomes concerned that David may be becoming too interested in Donna, but he assures her that his interest is purely professional and that he and his fiancée are planning to marry soon. Posing as Donna, one of Vince's girl friends phones the police to implicate Josie in some recent car stripping incidents. While Donna is working at the school's farm area, a local teenager, Jackie Dodd, approaches her and she agrees to meet him later in the equipment shed. That night, Donna and Ruth, the only friend Donna has made in the school, meet the boys and enjoy dancing to music from a radio Jackie has brought. David sees the girls, but does not report them, then suggests to Trimble that he organize an officially sanctioned dance to which local boys will be invited. David involves Donna in organizing the event, which proves to be a great success. After Josie is sentenced to the school, she tells all the inmates that Donna informed on her and the girls further harass Donna, but she refuses to say anything to Trimble. When Ruth is hit by a baseball bat, intended for Donna, she is taken to the school's hospital. While David questions Donna in his office about the incident, she steals a pair of scissors, which she uses to defend herself when a number of the girls gang up on her. As Donna is now in danger of being transferred to the state prison, David persuades Ruth to confide in him, but they are overheard by another girl who informs Josie that Donna may be about to identify Vince. After Josie phones Vince, he decides to come to the school himself to deal with Donna. Josie then advises him to find Jackie, who can get him over the fence. At knifepoint Vince orders Jackie to drive him to the school. Meanwhile, Josie and the others are trying to break Donna out of solitary confinement in time for Vince's arrival. When Jackie discovers that Vince is after Donna, he tries to grab the knife from Vince and in the ensuing struggle, the truck crashes into the school's entrance gate. Jackie and Vince continue to fight in the driveway until officers break them up and arrest Vince. Later, while Donna and Jackie are dancing happily at another school party, Trimble tells David that all charges against Donna have been dropped.