Geronimo Stilton, publisher of "The Rodent's Gazette" in New Mouse City, travels with his friends to the Ratlapagos Islands in search of treasure, and soon begin to suspect they are not the only ones involved in the quest.
Geronimo Stilton and his family travel to Penny Pincher Castle to visit his uncle, Samuel S. Stingysnout, and tries to uncover who, or what, is behind the creepy occurrences that have been taking place at the castle.