Cady Heron, having been homeschooled in Africa, transfers to North Shore High School in Chicago. Unsure of how to fit in, she quickly befriends outcasts Janis Sarkisian and Damian Hubbard, who warn her about the school's most feared clique, The Plastics, led by the manipulative Regina George, with members Gretchen Wieners and Karen Smith. They convince Cady to infiltrate The Plastics as a way to undermine Regina's reign. As she spends more time with The Plastics, Cady begins to adopt their manipulative behaviors, losing touch with her original friends.