Pilkey introduces his protagonists, George and Harold. George has a flat head and wears a tie, and Harold wears a T-shirt and has a bad haircut. George and Harold are in the same fourth-grade class at Jerome Horwitz Elementary School. They get in trouble and have a significant “silly streak.” A series of illustrations depicts George and Harold changing the sign reading “Flower Shop: Pick Your Own Roses,” to “Flower Shop: Pick Our Noses” (1-2).

After school, Harold and George usually go to the treehouse in George’s backyard. They spend most of their time here creating comics: George loves writing stories, and Harold loves to draw the accompanying illustrations. Their favorite comic book character, who they co-create, is Captain Underpants, an underpants-wearing superhero who fights crime. George and Harold sneakily used the school’s copy machine to print copies of their Captain Underpants comics, which they sold to other students.

Chapter 3 contains an illustrated, comic-book-style version of one of Harold and George’s creations. In this edition of the comic, a stinking pile of cafeteria taco mix, called the Inedible Hunk, comes to life at an elementary school. Captain Underpants comes to help. The city praises him for his role in fighting bad guys (all other superheroes are too elderly to intervene).