Scholastic, 2015. — 225 p. — ISBN: 9780545747424, ISBN: 9780545520492.
Pee-yew! What's that pong? It's a letter from Thea - she's in danger! Geronimo's sister has disappeared during a treasure hunt on Easter Island. Armed with a map and some cryptic clues, Geronimo and his friends rush to the rescue. Will they find Thea before she and the treasure are lost furever?
When you're with Geronimo Stilton, it's always a fabumouse adventure!
New Mouse City was in danger! An evil professor was threatening us all with his terrible inventions. The authorities called upon me, Geronimo Stilton, to thwart his plans by traveling on a top secret mission — to outer space! I was totally unprepared to go. But moldy mozzarella, my trip was out of this world!