Book Description: Enter the world of Geronimo Stilton, where another funny adventure is always right around the corner. Each book is a fast-paced adventure with lively art and a unique format kids 7-10 will love.My sister, Thea, is the mystery-loving rodent, not me! But somehow I found myself going undercover to get to the bottom of a case. Slimy Swiss balls -- I hardly knew where to start! Geronimo Stilton, Secret Agent Mouse? Maybe I could get used to that. . . .