Morris "Mud" Himmel and his friends are faced with the dreaded prospect of being sent to various summer camps that their parents have chosen for them, none of which are appealing. In a bid to avoid this fate, they come up with an elaborate plan to create a fake summer camp where they can enjoy total freedom. With the help of Dennis Van Welker, a former drama teacher and aspiring con man, they use their savings to rent a deserted hippie campground. Each of the kids convinces their parents that it's a legitimate, specialized camp, catering to different interests like fat camp or military camp, and they temporarily escape their parents' control.

As the kids settle into their self-made paradise, they experience the joy of independence, creativity, and friendship, transforming the rundown camp into a lively haven. They set their own rules, engage in wild activities, and bond over their shared secret. However, maintaining the illusion to their parents proves increasingly challenging. Dennis's erratic and unpredictable behavior, coupled with a series of close calls, threatens to expose their ruse. As the summer progresses, they learn valuable lessons about responsibility, teamwork, and the importance of honesty.