Now, the trio must venture far beyond the safe and cozy dirt floors of the post office basement and explore the big world--a world filled with zooming cars, pouncing cats, hungry foxes, and lots of humans Along the way, they meet a clan of super mean mice at the store next door, and some very smart mice at the local library. They make new friends, like the loyal and helpful Buttercup, (a brave boy dog who hates his name, for obvious reasons), a gossipy squirrel named Chitchat, and even some human children. It's a race against time, but with the help of their new friends and their newfound gift of gab, these clever mice just may come up with a plan to save the post office and unite all of their animal friends too.