The rainmaking machine has done its evil work; Simon has shrunk everyone to the size of his thumb, even his henchman Cad. Panic soon grips the city. Underdog and Polly arrive with a plan to capture Simon and make him reverse his formula. Underdog and Polly lead the citizens into the backyard of Simon's lab. Using a leaf, a strand of Polly's hair and a spider's web, our hero swings down and- using his makeshift violin- sends the demented scientist softly to dreamland. While Simon sleeps, Underdog grabs a hold of the shrinking water bottle and pours enough of the solution to shrink Simon to the size of a flea. When Simon wakes up, he tickled by Underdog and Polly until he gives up the antidote. Soon, everyone is back to his or her normal size and Simon and Cad are turned over to the law.
