The adventures of Captain Underpants: 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. Captain Underpants and the perilous plot of Professor Poopypants: When Professor Pippy P. Poopypants comes to Jerome Horwitz Elementary School to teach science, he goes off the deep end because students make fun of his name. Only Captain Underpants can save the school from the professor's perilous plot.

Two stories bound back-to-back and inverted. Author's name on Captain Underpants and the perilous plot of Professor Poopypants title page is crossed out, with Gidget Hamsterbrains printed below.