Presents the further adventures of a motorcycle-riding mouse who goes to school and becomes the instigator of an investigation of rodents and the peacemaker for two lonely boys.

Penny feels guilty after taking a beautiful blue marble that she sees in Mrs. Goodwin's grass, but gets a pleasant surprise when she goes to return it the next day.

Chester and Wilson share the same exact way of doing things, until Lilly moves into the neighborhood and shows them that new ways can be just as good.