George and Harold and their doubles, Yesterday George and Yesterday Harold, have been taking turns going to school, but when the doubles fall prey to their gym teacher, Mr. Meaner, and his method of mind control that turns students into attentive, obedient, perfect children, it is up to original George and Harold to strike back.

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.

General Jackrabbit and his Robo-Rabbits from Jupiter attempt to take over the world on Ricky Ricotta's birthday.

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.

Ricky Ricotta, his Mighty Robot, cousin Lucy, and some friends set out to save mousekind from Stupid Stinkbugs from Saturn, with a little help from some special gum and taffy.

A small mouse named Ricky Ricotta and his best friend, a giant flying robot, save the world from Victor Von Vulture and his vicious Video Vultures from Venus.

Having changed the course of human history after unwittingly wondering what could be worse than going to prison, George and Harold are shot through time back to kindergarten, where they are subjected to bullying and a clueless school principal.

A snotty situation ensues when Melvin Sneedley, an academically-gifted student, turns into the Bionic Booger Boy and must be stopped by George, Harold, and 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.

When a new sitter arrives and a movie star goes missing, Dog Man and Cat Kid investigate, but Petey, the world's most evil cat, complicates their case.