The story is about four unusual mice thrown together on a life-changing adventure when the land around the Ancient Oak breaks away from the shore and floats off on the ocean - creating The Traveling Island.
When they discover a mysterious room inside one of the tree's roots containing a miniature sword and a scrying crystal, it is clear that magical forces are at work.
The four face many dangers, and unintentionally trigger a terrible fate for their ex-neighbors in the Fieldmouse Village. Bravely, they return and try to balance the fate, though it may mean sacrificing their very lives.