Geronimo Stilton, the best reporter in all of Mouse City, is now the editor-in-chief of the popular newspaper The Rodent's Echo. He manages to secure the most important interviews. This time, he is called to interview Prince Noguinda. However, his interest is suddenly diverted by the mysterious disappearance of two rare lizards from the city museum. The situation becomes complicated, and Geronimo is determined to find the thief. In his quest to solve the case, he will uncover the great secret of Prince Noguinda.