My sister, Thea, is the mystery-loving rodent, not me! But somehow I found myself going undercover to get to the bottom of a case. Slimy Swiss balls -- I hardly knew where to start! Geronimo Stilton, Secret Agent Mouse? Maybe I could get used to that. ...

It was Christmastime on Mouse Island, and I couldn't wait to celebrate with my friends and family. Until I learned that they were all traveling out of town for the holidays, and I'd be spending Christmas alone! I was depressed, down, despondent, and starting to feel like a real grinch! I wandered the streets of New Mouse City, feeling sorry for myself. But then I discovered an amazing surprised that taught me the true meaning of Christmas.

Holey cheese, it was strange! All across New Mouse City, rodents kept telling me I'd done things I had no memory of. Was I going crazy? Had the cheese finally slipped off my cracker? No, that wasn't it. I soon discovered the truth: There was a Geronimo lookalike going around, pretending to be me! He'd even fooled my sister Thea. Worst of all, he was trying to take over The Rodent's Gazette! I had to get that greedy impostor's paws off my newspaper,...

Our second time-traveling adventure was in ancient Egypt. We were there to discover how the Great Pyramid of Giza was built. But when we got there, we were arrested by the Grand Vizier and taken to see the pharaoh - who had us thrown in the dungeon! Would we be able to escape, or would we be fed to the crocodiles?