The entire Mouse City is astonished by the behavior of Geronimo Stilton, the editor of the popular newspaper The Rodent's Echo. He insults his old friend and famous chef Richard regarding the exquisite cheese he uses in his restaurant and takes the spot of an elderly lady on the bus! Moreover, he doesn't stop there: he also steals a little girl's ice cream. Does Geronimo have a hidden second personality? Something strange is happening. Will Benjamin, Thea, and Trap be able to solve the mystery and clear the Stilton name?