Kate (Dominique Swain) is the girl everyone loves to hate. As has become tradition, everyday she meets her friends Casey (James Franco) and Nick (Eric Christian Olsen) after school to trash the kids they dislike. But today is no ordinary day. Today, Kate has just been in a violent fight with her little sister (Beverley Mitchell), and now she's got plenty on her mind. When she poses the question, "What's the worst thing you've ever done to somebody else," the guys realize they're in for some excitement. As they each reveal some humorous but cruel anecdotes about their pasts, the mood slightly tenses up, and their memories get more and more disturbing, to a point of no return. But, how much can they trust each other? Who really is the meanest? And most importantly, do mean people really get what's coming to them in the long run? Only Mean People Suck can answer.