In the 1943 invasion of Italy, one American platoon lands, digs in, then makes its way inland to attempt to take a fortified farmhouse, as tension and casualties mount.

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.

Charley and Edna are feeling very pleased with themselves and their new car. They decide to share their good fortune and offer to take six underprivileged children out for a fun day at the carnival. Unfortunately, the children come from Juvenile Hall, and each one is more trouble than the last.