Geronimo Stilton Special Editions Series by Geronimo Stilton

Geronimo unlocks the mystery in this fabumouse adventure -- which includes a bonus story! My sister, Thea, had discovered an enormouse old castle built by the founder of New Mouse City! She and Trap dragged me along with them to explore it. Inside, we found one hundred keys... but only ninety-nine doors to unlock. What mysterious room did the hundredth key open? It was up to us to find it and reveal its secrets! BONUS! After the story, read an extra Mini Mystery adventure and jokes galore!

The Colosseum is being haunted by a gladiator ghost. None of the tourists want to visit anymore! Geronimo must solve the mystery and rid the site of its ghost. *Plus BONUS Mini Mystery: The Cheese Burglar Can Geronimo clear his name and catch the real thief before it's too late?