Jim and his companion, the mouse Gran, operate an inn where they work diligently. One day, a strange individual comes to the inn and, upon departing, leaves a map behind. The map displays an island abundant with riches. Therefore, Jim and Gran set forth in their small boat, intent on realizing their aspirations and leaving the inn in the distance. However, it appears that others know of the map's existence, as they encounter Captain Silver and his unruly band of pirates. Jim, Gran, and their newfound ally, Kathy, strive to outdo them in the ensuing pursuit of the treasure.
