When an evil professor begins threatening New Mouse City with terrible inventions, Geronimo Stilton is enlisted by local authorities to embark on a top-secret mission to outer space to thwart a nefarious plot.

Geronimo sends valentines to all his friends but seems destined to spend the day alone.

Geronimo Stilton is entered in the Mouse Island Marathon by his friend Champ Strongpaws who then forces him to train for it.

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.

Holey cheese, it was strange! All across New Mouse City, rodents kept telling me I done things I had no memory of. Was I going crazy? Had the cheese finally slipped off my cracker? No, that wasn't it. I soon discovered the truth: There was a Geronimo lookalike going around, pretending to be me! He even fooled my sister Thea. Worst of all, he was trying to take over The Rodent's Gazette! I had to get that greedy impostor's paws off my newspaper, but...

When Geronimo's crush Petunia Pretty Paws gives him a crystal figurine of a boat as a gift, he had to accept it. But oh, was it ugly, but then he discoverers a piece of paper inside with a mysterious message from someone living in Venice, asking for help! So off Geronimo Stilton goes to do whatever it took to save the day!

When Geronimo Stilton learns someone wants to steal the antique silver skates being offered as a prize in Mouse Island's annual winter Ice Skating Championships, he races to uncover the mysterious thief and save the prize.

"Rancid rat hairs, the cat pirates are coming to town! They're planning on stealing New Mouse City's Statue of Liberty and taking it back to Cat Island. They think it's completely made of gold! My friends and I are determined to protect our city's precious symbol. But can we stop these fearsome felines?"--Page [4] of cover.

"Moldy mozzarella! It was only a few days before Halloween when all of the pumpkins in New Mouse City disappeared. A thief was on the loose, and there was only one person I could count on to help me solve this peculiar mystery--my detective friend Hercule Poirat. But would we be able to figure out what was going on in time to save Halloween?" -- p. [4] of cover.

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.