George Beard and Harold Hutchins are back with their hilarious fourth-grade adventures! When their new science teacher, Professor Pippy P. Poopypants, gets fed up with everyone laughing at his name, he creates a diabolical machine to force the whole world to adopt silly new names. With their homemade comic books, the boys accidentally bring their superhero creation Captain Underpants to life once again. Now they must stop Professor Poopypants' ridiculous revenge plot before everyone in the world is stuck with embarrassing names forever!