Principal Krupp turns into Captain Underpants to star in the first four books of the series featuring the superhero principal and the students of Jerome Horwitz Elementary School. Just when they thought they were out, it pulls them back in! Our Heroes beat the Bionic Booger Boy, but they forgot about those rascally Robo-Boogers. Join George, Harold, Mr. Krupp, Melvin Sneedly, and Sulu the Bionic Hamster on an adventure that will take them into the deepest regions of outer space and back through time to the mysterious and uncharted world of the day before yesterday! It is a monster-mashin, Robo-wranglin, time-traveling, brain-switchin, nose-pickin good time!