Ricky Ricotta, a small mouse, is being bullied at school, but when he rescues a powerful robot from its evil creator, he acquires a friend and protector--and saves the city from Dr. Stinky.

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.

By flipping the pages, the reader may view animated illustrations that follow Ricky Ricotta, a small mouse, his giant flying robot, and his annoying cousin Lucy as they battle the nightcrawlers from Neptune that are invading through a wormhole.

George and Harold hypnotize their principal who, believing he is the superhero Captain Underpants, leads them to the lair of the nefarious Dr. Diaper. They must then defeat his evil robot henchmen.

Evil Uncle Unicorn attempts to dominate earth by using a Ladybot to trick Mighty Robot.

When Professor Pippy P. Poopypants comes to Jerome Horwitz Elementary School to teach science, and 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.

"Petey the Cat is out of jail, and he has a brand-new lease on life his Petey's reevaluated what matters most, Li'l Petey is struggling to find the good in the world. Can Petey and Dog Man stop fighting like cats and dogs long enough to put their paws together and work as a team? They need each other now more than ever -- Li'l Petey (and the world) is counting on them!"--Publisher.

Only Captain Underpants can stop the three evil space aliens who have invaded Jerome Horwitz Elementary School and turned everyone into lunchroom zombie nerds.