The story is about a mouse named Geronimo Stilton who is an editor of a newspaper. He is also the author of this book. His sister Thea finds a treasure map so they go on a boat to try to find the treasure. The treasure is the Emerald Eye which they think is some sort of jewel. Their cousin Trap and their nephew Benjamin also come on their adventure. Then, their ship sinks and they land on an island which just happens to be the right one. Geronimo and his family work together to follow the map and find the treasure.