Geronimo Stilton has been invited to an art show at the house of a world fa<i>mouse</i> painter. When Geronimo notices the artist acting strange, his whiskers begin to twitch. Why is the painter so keen on avoiding Geronimo's friend, a bumbling inspector? Before he knows it, Geronimo receives a note that leads them to a mysterious message hidden within a group of paintings. But in order to crack the code, Geronimo will have to buy the paintings, so they'd better solve this mystery before he goes broke! Who could be sending Geronimo on this wild mouse chase?