Best pals Penrod and Sam are leaders of a super-secret neighborhood society, the In-Or-In Boys Club. Troubles arise when a pompous prig tries to join the club and when the boys lose their clubhouse in a land sale. But there’s also plenty of time to play pranks, put on a carnival, experience the pangs of first love, and romp with Duke, the world’s best dog.

Young Bill Emory is a typical mischievous, rambunctious boy, but his father William is a strict disciplinarian, and Bill is constantly being punished for simple childhood transgressions. Finally Bill can take no more of his father's excessive punishments and runs away. Complications ensue.