More than 18 million Geronimo Stilton books in print! I was just minding my business at home when I got a telephone call. It was my uncle Samuel S. Stingysnout, inviting the whole Stilton family to creepy, faraway Penny Pincher Castle for a big surprise. Moldy mozzarella -- I'm not much of a traveling mouse, and I hate surprises. But Thea, Trap, and Benjamin were going, so I couldn't say no. I could tell this was going to be one super-spooky trip!