Malcolm, an orphaned field mouse, is considered a nuisance by his house-mouse relatives who live at 65 Rodent Row, Mouse-Town Estates, in the gloomy basement of Balmoral Castle. He is a misfit who does poorly at school and is bullied by his cousins. While house mice serve as collectors within the castle walls, Malcolm yearns to follow in his daddie's paw-steps and become an explorer of the outside world. While collecting in the royal kitchen one afternoon, Malcolm is discovered by Chief Castle Cook. In his mad dash to escape, Malcolm inadvertently exposes the MI Mouse-Way Ramp 3 to human eyes. Disaster strikes! Royal staff board up mouse holes and bait traps with poison. Mouse-Town Estates is threatened with death and starvation. Malcolm seizes the opportunity to try to save the house-mouse community and to explore the outside world at the same time. Will Malcolm survive four fat royal corgis, being trapped in the royal handbag, arrest, and imprisonment to save the day? Or will Her Majesty the Queen succeed in chopping off his head?