Biblioden, founder of the Evil Librarians, is back to complete his goal of world domination and it is up to Bastille to lead the charge against him.

Still yearning to be seen as heroes, Wolf, Shark, Snake, and Piranha set out to rescue ten thousand chickens from a high-tech cage farm--but one unexpected problem is Mr. Snake himself, also known as "The Chicken Swallower."

After graduating from the superhero academy, Melvin Beederman heads for Los Angeles, where he unexpectedly teams up with Candace Brinkwater, school play actress, to nab the evil McNasty Brothers.

"George and Harold are behind bars for a crime they didn't commit! But just as they are settling into their new life, they are pulled from prison by a time-traveling tyrant named Tippy Tinkletrousers! Now the boys are taking a trip back in time to the carefree days of kindergarten, when the scariest thing they had to face was not evil mad scientists or alien cafeteria ladies but a sixth-grade bully named Kipper Krupp, the nephew of their clueless...

When Harold and George turn fourth-grade teacher Ms. Ribble into the evil Wedgie Woman, she gives the wedgie of doom to unsuspecting people who stand in her way--including principal-turned-superhero Captain Underpants.