Josie Geller (Drew Barrymore) is an insecure copy editor for the Chicago Sun-Times who has never had a real relationship. One day, her editor-in-chief, Rigfort (Garry Marshall) assigns her to report undercover at a high school to help parents become more aware of their children's lives.
Her first day at South Glen South High School is miserable. Josie reverts to the old geek persona that ruined her first high school career. She also has an unfortunate run-in with three obnoxious popular girls (Jordan Ladd, Jessica Alba, and Marley Shelton), and Guy Perkins (Jeremy Jordan), the school's most attractive, popular student. Josie loses hope, but is reassured when a kind-hearted nerd named Aldys (Leelee Sobieski) befriends her. Aldys, who loathes Guy and his gang, invites Josie to join The Denominators, a group of intelligent students.