Morris "Mud" Himmel (Jonathan Jackson) spends every summer at computer camp, but he hates it. Mud and his friends (Andrew Keegan, Melody Kay, Marnette Patterson), unhappy about their respective camp prospects, devise a plan to finally have a fun summer. They bribe Dennis Van Welker (Christopher Lloyd), an ex-teacher, to pose as a counselor for a fake camp and rent a campground where the kids can run amok. But they run into trouble when their parents want to come for a visit.