Description
On the morning of her 17th birthday, high-school senior Liz Purr, the most popular girl in Reagan High, is kidnapped in her bed by three masked assailants, one of whom stuffs a jawbreaker into her mouth as a gag before she is placed in the trunk of a car. The kidnappers turn out to be Liz's "friends"—Courtney, Marcie, and Julie—playing a cruel prank on her for her birthday, which they do annually. When the girls drive up to a diner to treat Liz to breakfast, they open the trunk and discover she is dead, having choked to death on the jawbreaker Courtney had used to gag her.
Julie wants to go to the police, but Courtney forbids her. Courtney calls the school pretending to be Liz's mother and tells them Liz is ill and cannot attend school, then the three go to school as though nothing had happened. Fern Mayo, school outcast and fervent admirer of Liz Purr (whom she calls "The Cat's Meow"), is sent by the school principal, Miss Sherwood, to deliver Liz's homework at the end of the day. She stumbles upon the three girls at Liz's house trying to arrange her body in bed. Courtney tries to fabricate a story that Liz died at the hands of a rapist.
Fern attempts to flee the house, but the girls catch her and Courtney buys her silence by accepting her into the clique, telling her to take Liz's place, despite Julie's protests. Courtney and Marcie give Fern a makeover, transforming her from plain and awkward to elegant and beautiful. The transformation is so complete, Courtney introduces Fern as the beautiful exchange student "Vylette".
Julie, overwhelmed by guilt at her part in Liz's death, breaks away from the clique, only to be reviled by Courtney and Marcie. As her popularity dissolves, she becomes a new target for abuse and contempt throughout the school. Her only real friend during this time is her boyfriend, a drama student named Zack.
As Vylette's popularity soars, Julie watches in silence as Courtney spins an endless web of lies to cover up the murder and maintain her popularity. Julie threatens to go to the police and tell the truth, but Courtney retorts that she, Marcie, and now Vylette will claim Julie killed Liz if she attempts to expose them. To her disgust, Julie learns that, after they had returned Liz's corpse to her house, Courtney went out that same night and seduced a stranger at a sleazy bar and had sex with him in Liz's bed in order to frame him for the murder.
Vylette becomes intoxicated with her new-found popularity, which has eclipsed Courtney's own. Courtney orders Vylette to learn her place, but Vylette vows that if Courtney does not watch her step, then she will reveal the truth behind Liz's death. In response, Courtney and Marcie post enlarged yearbook photos of Fern Mayo all over the school with the message "Who is Vylette" written on them, revealing Vylette's true identity and leaving her humiliated by the entire school. Julie takes pity on Fern and forgives her for being corrupted by Courtney.
Feeling remorseless for the lives she has destroyed, Courtney attends the senior prom with Liz's boyfriend, jock Dane Sanders. Meanwhile, Julie is at home going through a bag of Liz's belongings that were given to her. She finds a recordable greeting card she was fiddling with when Courtney was faking Liz's death scene, on which Courtney's admission to the killing was inadvertently recorded. Armed with this evidence, Julie, Fern, and Zack hurry to the prom.
When Dane and Courtney are announced as Prom King and Queen, Zack sneaks backstage and broadcasts Courtney's confession over the sound system. Shocked and disgusted, Dane abandons Courtney while Marcie hides under a table. Horrified that her scheme has been exposed, Courtney races for the exit as the rest of the furious students pelt her with corsages, calling her names, and use profanity. Julie snaps a picture of the devastated Courtney to immortalize the occasion. The film ends with Fern's quote to Detective Vera Cruz, "This is high school Detective Cruz. What is a friend anyway?", and the yearbook closes.