The Plastics disband over summer vacation: Regina joins the lacrosse team to deal with her anger, Karen becomes the school weather reporter, and Gretchen joins the "Cool Asians" clique. Aaron graduates from high school and attends Northwestern University while starting a relationship with Cady, who visits him during the weekends. Janis begins dating Mathlete Kevin Gnapoor, whom she initially disliked. As Cady reflects on the social peace that has taken over North Shore High, a group of new "Junior Plastics" has arisen, and Cady imagines them being hit by a bus as Regina was.