After being home schooled in Africa, Cady Heron moves to a high school in the United States. Her parents are zoologists, and she believes that she knows about survival of the fittest. However, she is surprised to learn that surviving in “girl” world in much different then surviving in the jungle.
On her first day at school, Cady makes friends with two students, Janice and Damien, who are not considered part of the “in-crowd”. They are actual friends to Cady, and they try to give her advice and help her transition into a normal high school. They teach her about the different cliques of the school, and warn her to stay away from “The Plastics”. The Plastics, led by Regina George, are a group of snobby, selfish, rich girls who believe they are the popular girls. However, they are only the popular group because everyone else is scared of them.
Although Janice and Damien warned her to stay away from The Plastics, Cady makes an impression on them and was invited to eat lunch with them. They invited her to eat lunch every day and follow all their silly “girl-world” rules. She quickly became the 4th member of The Plastics. Cady originally entered the group with the intentions of spying on the other girls and then telling Janice and Damien about what they did. However, Cady became obsessed with the spot light constantly being on her and became an actual member of The Plastics. She started learning all the new fashion trends, dressing “skanky”, and making fun of other students.
Cady falls for a senior in her math class named Aaron Samuels. He is Regina’s ex-boyfriend and she promises Cady that she will talk to him and help her out. However, Regina has cruel intentions on her mind, and she begins dating Aaron again, just to spite Cady. Cady has no choice but to accept this, because she wants to remain a part of the “in-crowd”.
Janice, Damien, and Cady devise a plan to tear apart Regina George and the rest of The...