The Onioneers are on winter camp, and Lemony is hoping to win all of the merit medals. But she and Mr. Highpants get stuck on top of Mt. Onion. Now Yakkity, Keo and Wanda must save them.

Yakkity is charged a fine when the library realizes that he hasn't returned a book called ""Darn-it Dog"" which he checked out over 10 years ago. Rather than pay the fine or give back his favorite book, Yakkity lies and claims that he never checked out the book. Eventually Yakkity begins to lie about everything to get what he wants.

Yakkity, Keo and Lemony are teamed together on a school project designed to help the town smell better. Lemony completely takes over the project when she decides to make use of some discarded oil by turning into a new lemon-scented fragrance. Lemony is praised and awarded for her unique creation until Yakkity and Keo discover that the oil in the perfume can turn people into human balloons.

Yakkity becomes a bike-riding ice cream salesman. But he starts eating all the merchandise (which counts as stealing) in order to get free stuff.

A soapbox race is announced, and the prize is a year's supply of Professor Crazyhair's Egg Salad. When Lemony forms a team with Keo, Yakkity eventually pairs with a peculiar new neighbour.