The Treasure of Easter Island (Geronimo Stilton #60‪)‬

"Each Geronimo Stilton book is fast-paced, with lively full-color art and a unique format kids 7-10 will love.

Holey cheese -- my sister, Thea, was in danger! She had traveled to Easter Island in search of a secret treasure, and now she needed my help. There was no time to lose! My friends and I hopped on a plane to begin our search, aided by a map and a mysterious riddle. What an exciting adventure!"