When George and Harold hypnotize their principal into thinking that he is the superhero Captain Underpants, he leads them to the lair of the nefarious Dr. Diaper, where they must defeat his evil robot henchmen.

When Mr. Lincoln, "the coolest principal in the whole world," discovers that Eugene, the school bully, knows a lot about birds, he uses this interest to help Eugene overcome his intolerance.

When George and Harold use their traveling purple potty to travel to another dimension where the school is nice and the principal, Mr. Krupp, thinks they're funny, they meet up with their evil twins and must face their cleverest enemies ever -- themselves.

Principal Krupp once again turns into the superhero Captain Underpants in order to save the world, and Jerome Horwitz Elementary School, from the evil talking toilets and the Turbo Toilet 2000.

George and Harold have really done it this time-- they've created a monster! She's faster, smarter, and more evil than anything the world has seen before--she's Wedgie Woman! With the help of her horrible robots and her horrendous hairdo, Wedgie Woman is on a mission to take over the world, and she'll give a whopping wedgie to anyone who stands in her way--including Captain Underpants.

Fourth-grade class clowns George Beard and Harold Hutchins have created the greatest superhero in the history of their elementary school --and now they're going to bring him to life. Meet Captain Underpants, whose true identity is so secret even he doesn't know who he is.

The six horrible Herdmans, the worst kids in the history of the world, cause mayhem throughout the school year.