From the outside, Harold is an average third grader growing up in the 1960s. Bored by school. Crushing on a girl. Likes movies and baseball. Enjoys spending time with his grandfather. But inside Harold's mind, things are a lot more unusual. His thoughts come to him as birds flying through a small rectangle in the middle of his brain. He visits an outdoor cafe on the moon and is invited aboard a spaceship by famed astronomer Carl Sagan. He envisions his own funeral procession and wonders if the driver of the hearse has even been born yet. Harold documents the surreal, hilarious, and thought-provoking ruminations of the title character during a single day in class.