It was Christmas time on Mouse Island, and Geronimo couldn’t wait to celebrate with his friends and family. Until he learned that they were all traveling out of town for the holidays, and he’d be spending Christmas alone! Geronimo was depressed. He was down and despondent, and he was starting to feel like a real grinch! He wandered the streets of New Mouse City, feeling sorry for himself. But then he discovered an amazing surprise which taught him the true meaning of Christmas.Geronimo Stilton is a mouse and the editor of the newspaper The Rodent's Gazette. Beginning his adventures, Geronimo's sister Thea invites him on a treasure hunt. Well, who can resist that? Certainly not Geronimo, who joins Thea and their cousin Trap on a sea voyage to the island on the treasure map.