Mousetopia's hero, the stalwart beetle Rug Bug, has finally made a home for himself in the mouse colony. Happily settled, he enjoys his work with his friends at The Cheeze Wheel, a local restaurant. But one day, Mousetopia is struck by a violent housequake that damages the city's light source, the Light-Mirrors, and cuts off the mice from the rest of The House.

To rescue his friends, Rug Bug seeks out the Mousetopian's former overlord and newest ally: The Head-Honcho General Fat Rat Bart of Rat City. What Rug Bug does not realize is that this decision could place Mousetopia in the clutches of another, more dangerous tyrant: Queen Dottie of Geometric City! With the balance of peace in The House at stake, can Rug Bug and the Mousetopians protect themselves from this new threat?