Benjamin Krupp is the principal at Jerome Horwitz Elementary School in Piqua Ohio. Krupp, along with the other teachers, are cruel to the students around them. Two students that especially get on Krupp's bad side are fourth grade students George Beard and Harold Hutchins, the school's pranksters. George and Harold also create comics, and create their most popular comic, Captain Underpants. After getting caught on camera committing their pranks, and forced to basically become Krupp's slaves, George and Harold get a hypno-ring that they use to get out of trouble. Then they decide to use the ring to convince Krupp that he is Captain Underpants, which turns out badly for them. Krupp becomes Captain Underpants whenever someones snaps their fingers, and turns back when water is dumped or spilled on him. Captain Underpants is the opposite of Krupp. Where Krupp is mean and abusive, Captain Underpants is kind and always trying to help people. Captain Underpants is also incredibly dumb, which doesn't help out during adventures. In the third book, Captain Underpants and the Invasion of the Incredibly Naughty Cafeteria Ladies from Outer Space (and the Subsequent Assault of the Equally Evil Lunchroom Zombie Nerds, Captain Underpants gains superpowers from Extra-Strength Super Power Juice, which the boys found on the main antagonist of the book's spaceship. Book 5, Wrath of the Wicked Wedgie Woman, Krupp is revealed to be Jewish. In Book 6 and 7, Krupp switches bodies with Melvin Sneedly using a device Melvin created. When they switch back, Melvin has stolen Captain Underpants' powers, but Captain Underpants does heroics without his powers. Eventually it gets fixed, and he gains his powers back. In Book 8, alternate universe versions of Harold, George, and Captain Underpants (all evil) are brought to the regular universe, and cause massive havoc, and by the end of the book, although the evil versions are sent back, the non-evil versions are all sent to jail for their crimes. Due to some time shenanigans from Tippy Tinkletrousers (the new name of Professor Poopypants from Book 4), Mr. Krupp was fired as principal when Harold and George were kindergartners, and Captain Underpants never existed. Book 10 has Tinkletrousers travel back in time to fix the timeline, making the 9th book not matter. Harold, George, and Mr. Krupp go back to the Cretaceous period, followed by Tinkletrousers. Book 11 ends with Mr. Krupp and all of the other teachers being put into an institution, since all of them have become a little crazy. Book 12 has all the teachers, led by the gym teacher Mr. Meaner, who has become smart, go back to school and take it over. He transforms all the students into obedient slaves, and begins selling the same product across the city to do the same to all kids. This last book ends with Krupp being unable to turn into Captain Underpants anymore, and just being normal Mr. Krupp now.