Geronimo, Thea, and their cousin Trap explore an old castle built by Grant Gentlemouse, the founder of New Mouse City, and when they find one hundred keys and only ninety-nine doors inside, they set off in search of the missing room.

When the Black Papyrus, an ancient artifact believed to reveal the secret of eternal youth, disappears from New Mouse City's Egyptian Mouseum, the director asks Geronimo Stilton to investigate.

Geronimo Stiltonix takes MouseStar 1's broken computer to a distant planet to be repaired by a brilliant inventor, but pirate spacecats attack and steal the device, and the spacemice must retrieve it before the machine can be turned against them.

With the help of Professor Paws Von Volt's new time machine Geronimo is whisked away on another adventure through time.

Geronimo Stiltonord has trouble selecting a winner as the judge of the Shield Mouselet Mega Challenge, and while everyone is distracted by the competition, the dragons launch a surprise attack.

Asked by a Bollywood star for help protecting a valuable ruby, Geronimo Stilton and Hercule Poirat are inadvertently cast in the actress's film in spite of limited acting skills and are horrified when an anonymous thief makes off with the ruby.

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

Geronimo heads to Penny Pincher Castle for some much needed vacation time, but his uncle puts him to work instead.

When Professor Cheesewheel automates Geronimo's house to help him keep it clean, Geronimo soon finds his futuristic home going haywire.

Geronimo Stilton's ancestor, Geronimo Stiltonoot, searches for Tiger Khan's missing flag to prevent chaos during the annual cavemouse sports competition.