In this story, George, Harold, Sulu, and Crackers accidentally end up in an alternate universe where the whole world is the opposite of their normal world. Good is bad, smart is dumb, and heroes are villains.

Get ready for action, laffs, and shockingly offensive violence, as Captain Underpants faces off against his horrible evil twin, the terrifying Captain Blunderpants.

Will George and Harold be able to stop a vicious plan that threatens to destroy the Earth? What will happen to Sulu and Crackers after they are kidnapped and turned into fiendish gangster thugs? HOW will mankind survive when Captain Underpants LOSES his super powers? And who the heck is "Boxer Boy" and "Great Granny Girdle"???

Find out the answers to these questions, and much, much more when your read the book!