When a sorority girl is found murdered, her classmates set out to solve the case.

Paula Canfield, a member of the Gamma Theta sorority, is despised by the other girls because of her selfish and spiteful nature. Paula has many enemies at the girls school she attends, and even has alienated Miss Grace Thornton, a kind, considerate teacher at the school. Miss Thornton and Paula's widowed father Horace are contemplating marriage, but Paula does everything in her power to block it. At the sorority house, Jane Peters, one of the girls, anxiously awaits a phone call from her soldier boyfriend who is home on leave. When Paula answers the phone, she ignores Jane and tries to wrangle a date with the soldier herself. Mary O'Ryan, another Gamma Theta, overhears Paula's conversation and informs Jane about it. Alice Blake, another sorority member, detests Paula because she has threatened to tell Alice's impoverished parents about a loan Paula has made to their daughter unless Alice agrees to write Paula's thesis and complete the rest of her homework. The other five members of Gamma Theta each have their own reason for loathing Paula. On the weekend that the girls are to stage their initiation cermony at a mountain cabin, Paula fails to appear. Later that evening, a radio broadcast reports that Paula's body has been found in a canyon, murdered. When Jane arrives at the cabin with a bandaged hand and a bloodstain on her leg, the girls become suspicious, but Jane claims that her car had a flat tire and she cut her hand on the jack. Just as the girls decide to cancel their initiation and return home, police captain Addison Brooks and his assistant Walter Cummings arrive to investigate Paula's death and ask them to remain at the cabin. When Brooks announces that Paula received a phone call from a unknown woman right before she was murdered, the girls begin to suspect one another. While searching the cabin for clues, Mary finds Paula's compact, but is struck from behind by an unseen assailant, who then disappears with the compact. The next afternoon, Brooks returns and hands Cummings a plaster cast of a shoe worn by Paula's murderer. Later that night, under cover of darkness, Miss Thornton, the girls' chaperone, throws a pair of shoes in the furnace. When the shoes are found, Miss Thornton tricks Mary into writing a confession that she was the one who phoned Paula. The teacher plans to poison Mary with sleeping pills and then hand the confession to Brooks, but she is interrupted before she can complete her plot. The next day, Brooks arrives to take the girls to headquarters for questioning. Mary is the last to leave the house, and when she finds that someone has tampered with her car by disconnecting some engine wires, she returns to the house and is met by Miss Thornton, who is holding a gun. Just as Miss Thornton calmly confides that she killed Paula and plans to frame Mary for the murder, Brooks enters the house and overhears her confession. After arresting Miss Thornton, Brooks explains that he emptied the bullets from the gun and left it to trap Paula's killer. Miss Thornton then breaks down and admits that she killed Paula because the girl stood in the way of her marriage.