Veronica is part of the most popular clique at her high school, but she disapproves of the other girls' cruel behavior. When Veronica and her new boyfriend, J.D., confront clique leader Heather Chandler and accidentally poison her, they make it appear a suicide. Soon Veronica realizes that J.D. is intentionally killing students he does not like. She races to stop J.D. while also clashing with the clique's new leader, Heather Duke .