Notes

Based on an original idea by Elisabetta Dami. Plus a bonus mini mystery and cheesy jokes! (Title page) Contents: The hunt for the hundredth key -- Mini mystery: the double cross -- Geronimo's jokes.
Summary: Geronimo, Thea, and Trap are exploring a mysterious old castle built by the founder of New Mouse City. Can they unlock all its rooms and discover its secrets?
Translated from the Italian.
Geronimo Stilton.