It's about a teenage girl, Cady Heron, who used to be home schooled in Africa but moves to the United States and has to go to a normal high school in Evanston, Illinois. On her first day at school, she hates it. She thinks it is a bit weird because she cannot go to the toilet when she wants, cannot write in green ink and has to stay in the same seat everytime she goes into a lesson. On the second day it becomes more successful as she makes new friends, Janice and Damian. When they skip a lesson, Janice and Damian give her a map of the school eating area. It is arranged into different sorts of people and their personalities. At lunch time Cady is on her way to sit with her new friends but is interrupted, then Regina, Gretchen and Karen ("The Plastics") ask her to sit with them and so she sits with them.