The world’s most fa-mouse painting is hiding a big secret! An X-ray of the Mona Mousa reveals a strange riddle. Solving the clues takes Geronimo to the most dangerous parts of the city, but facing the hair-raising rollercoasters and vicious octopuses is all worth it for the amazing treasure at the end of the trail. Isn’t it? About the Geronimo Stilton series: Geronimo Stilton is a bestselling children’s series with a dedicated international fan base. As seen on Netflix, the series follows the adventures of the Geronimo Stilton the fa-mouse journalist, as he searches for the next hot scoop. With illustrations and fun fonts throughout, Geronimo Stilton is perfect for reluctant readers aged 5+ years.