Spring becomes a memorable time for Miss Mackle's second-grade classroom because of the antics of Horrible Harry and the special insights of shy Song Lee.

As Valentine's Day approaches, the students in Room 2B are preoccupied with kickball and a possible wedding between Horrible Harry and Song Lee.

Doug discovers that though being Harry's best friend in Miss Mackle's second grade class isn't always easy, as Harry likes to do horrible things, it is often a lot of fun.

When their teacher ends up in the hospital, the members of class 2B find a way to include her in their holiday celebration.

Inspired by his third-grade class's study of the moon, Harry announces that he is going there.

When Horrible Harry's pet cat, Googer, sneaks a ride and gets into the school building, third-graders Harry and Doug have to catch him before anyone else does, which means going into some forbidden places.

On the last day of second grade, Song Lee's party at the local amusement park forces Harry to face his fear of elevators when he is expected to ride the Drop of Doom.

Horrible Harry, the class clown of Room 2B, returns to the spotlight with the Purple People, mysterious beings that only he can see.

When Sid, his annoying third-grade classmate, ruins Song Lee's origami praying mantis, Horrible Harry plots triple revenge on the troublemaker.

Nearly every kid in Room 3B is trying to get picked for the South School Safety Patrol Squad--especially Harry. Harry wants a star badge just like his grandpa's, so he works extra hard to be the perfect student: hanging up his jacket neatly, organizing the crayons in rainbow order, and--his favorite part--cleaning up sticky noodles off the floor after lunch. But Doug thinks someone is taking the power of Safety Patrol too far, maybe even using it...