Jo Mitchell attends North Shore High School in
Ohio, hoping to attend
Carnegie Mellon, her late mother's
alma mater. On her first day, she encounters a
clique called "The Plastics", composed of leader Mandi Weatherly, ditzy Chastity Meyer, and
hypochondriac Hope Plotkin. Jo befriends Mandi's rival Abby Hanover and they become embroiled in a
prank war. Jo's father is a mechanic who rebuilds engines for
NASCAR. As a result, she is a good mechanic and excels in shop class, where she falls in love with a boy named Tyler. Jo gives Abby a ride home on her
Vespa. She meets Abby's father, a successful entrepreneur, who offers to pay Jo's college tuition in exchange for friendship with Abby. Jo reluctantly accepts, motivated by her desire to attend Carnegie Mellon. Jo, Tyler, and Abby become close friends, along with a journalist named Quinn Shinn, who has become obsessed with the Plastics ever since she came to high school. Tyler takes Jo on a date, borrowing Mandi's boyfriend Nick's convertible. Unknown to them, however, the car is bugged, which Mandi uses to humiliate Jo. Jo later learns that Tyler is Mandi's stepbrother. Mandi escalates the prank war, first trying to sabotage her chances to get into Carnegie Mellon, then using
artificial sweetener and coffee to ruin one of Jo's father's engines. Jo confronts Mandi about going too far, only to learn she is focused on her narrow goal of being on top. So, when Jo and Abby realize she is about to throw her birthday party, Jo throws a rival party for Abby; Abby's party is "all invited", whereas Mandi's is "invite only". The Plastics, seeing no one at Mandi's but hearing music at Abby's, puts
ipecac on their pizza. Jo sees Hope paying for the pizza and notices its strange smell, before stashing it away. The Plastics are disappointed to see that no one at Abby's party is sick. Mandi's boyfriend Nick comments on the lack of food, prompting Jo give him a slice of the contaminated pizza. After Mandi kisses him, he vomits on her. Jo, Abby, and Quinn, who had been helping them, start a new clique called the "Anti-Plastics" and play a series of pranks on Chastity and Hope. Jo campaigns against Mandi for Homecoming Queen, threatening Jo's relationship with Tyler as she's becoming like her nemesis. Realizing what she's been doing is wrong, Jo tries to return the money to Abby's father. Mandi overhears this and gets Quinn to turn against her and write about the bribe in the school paper, which nearly puts Jo and Abby's friendship at a breaking point. Mandi and Nick steal the homecoming court charity money, which is to be donated to an animal shelter. Nick plants it in Jo's shed while Mandi tips off to Principal Duvall. Jo gets expelled, but not before she finds Mandi and challenges her to a game of flag football. Mandi refuses until she realizes she must win to remain popular. When Tyler and Abby learn from Quinn that Jo was likely framed, they rekindle their friendship with her and enlist the tech-savvy Elliott to prove Jo's innocence. Elliott finds video footages of Mandi and Nick planting the money and
texts them to the whole student body. The Anti-Plastics beat the Plastics at flag football. As Mandi and Nick are arrested, Principal Duvall apologizes to Jo for the misunderstanding and allows her to graduate. At the homecoming dance, Abby and Elliott are crowned King and Queen while Jo and Tyler kiss. Quinn takes over as leader of the Plastics. Mandi and Nick serve community service and are allowed to graduate, but lose their popularity. Jo and Abby attend Carnegie Mellon together while Tyler attends
Penn State. ==Cast==