George and Harold wont be able to participate in this years science fair. Thats because they glued Principal Krupp to his chair at last years science fair. But that wont stop them from messing with the science projects. So the electric dog washer shoots out black ink, the model volcano blows out butterscotch pudding, and the boys end up in detention. With time to kill, they create a new Captain Underpants episode, this one with attacking toilets. But when the school science genius turns the cartoon into reality, its time for Mr. Krupp to transform into everyones favorite underwear-wearing superhero!