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

Follows the school activities of second-graders, Harry and Doug, as they participate in a secret mission to celebrate "Charlotte's Web," learn how to make green slime, and put on a skit warning about the dangers of smoking.

Harry incorporates his fascination with earwigs into Miss Mackle's class project of acting out a fairy tale in front of the other third graders.

Horrible Harry sets out to discover who Miss Mackle is going to marry, and he takes some risky moves to be the first one to know.