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.
Harry leads a mission to place cobwebs all over school, shows the class how to make green slime, and stages a "deadly skit" that has everyone on the edge of their seats.
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.
