When his grandfather finds out he is bankrupt, Geronimo is sent off to Moldy Manor where his miserly Uncle Stingysnout teaches him to be better at saving.

Geronimo goes to Athens to report on the Olympics, and after observing some of the games he and detective Hercule Poirat become suspicious about Cyrus von Snootrat who seems to be winning every Olympic event and they decide to investigate him.

When Geronimo gets signed up for the Mouse Island Marathon by mistake, his friends and family do everything they can to make sure he finishes.

Bruce Hyena convinces Geronimo to join him in climbing Mount Kilimanjaro, a task for which the mouse journalist is completely unprepared.

Geronimo Stilton's ancestor, Geronimo Stiltonoot, investigates a witness's claim of a moving mountain of ice.

After saving a baby dinosaur from the river, Geronimo Stiltonoot discovers that it is incredibly mischievous and tries to find a way to get it back to its herd.

"A mysterious old friend of Grandpa Frankenstein shows up one night on the doorstep of Cacklefur Castle. He's a vampire - and he needs the von Cacklefur family's help. His ancient castle has been infested by strange and troublesome monsters and ghosts, and he's afraid he'll have to move out because of them! .... It's up to Creepella and her family and friends to help this vampire save his home"--P. [4] of cover.

When all the pumpkins in New Mouse City disappear days before Halloween, Geronimo and his detective friend Hercule Poirat investigate, as all the mice in the city receive invitations to a mysterious party.

Traveling to the planet Jurassix to warn its inhabitants of an imminent comet strike, Geronimo Stilton and his crew encounter ferocious, dinosaur-like beasts who have an appetite for rodents.

When Geronimo gets lost looking for hidden treasures in the Gobi Desert, he comes across giant dinosaur bones.