Geronimo is invited by his friend Creepella von Cacklefur to her family's spooky castle, and he is surrounded by the gloom of the castle as well as by Creepella's creepy family!

"My sister Thea and my cousin Trap were not getting along! When Grandfather found them arguing over who would get to join me on a trip to Brazil, he forced us all to go together. My friend Isabela needed my help finding a mysterious emerald. Could Trap and Thea stop shouting their snouts off long enough to help find the stone?" -- Back cover.

When the quest to find a cure to an epidemic targeting the citizens of New Mouse City is sabotaged, Geronimo Stilton must figure out who's behind it all before he ends up covered in blue spots too.

"The fair has come to Mysterious Valley! Creepella is looking to forward a fun, thrilling day of rides and games with her family and friends. But one spooky rollercoaster seems to be making everyone who rides it disappear! Creepella is determined to get to the bottom of the mystery -- but what will happen when she rides the coaster herself?" --

"Geronimo Stilton's ancient ancestor Geronimo Stiltonoot is back in another prehistoric adventure! It's the night of the big Cavemouse Idol competition, but Geronimo Stiltonoot isn't there. He has a cold, and goes to bed early. So when it's discovered that the contest's valuable grand prize has been stolen, Geronimo is the main suspect! He must prove his innocence . . . or he'll end up in enormouse trouble!" --