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.
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.
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.