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!

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. With only ninety-nine doors to unlock. What mysterious room did the one hundredth key open?

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 BurglarCan Geronimo clear his name and catch the real thief before it's too late?

From the bestselling middle grade series, a chapter book about a mouse journalist searching for a missing computer, plus a bonus short mystery and jokes. Grandfather William was throwing me, Geronimo Stilton, a party—it had been ten years since I published my first book! He wanted me to write a new book especially for the occasion. Then my laptop was stolen right from under my snout. Cheese niblets, how terrible! Could my friends and I find my computer and print my book all in time for the party? BONUS! After the story, read an extra Mini Mystery adventure: The Lake Monster. When a mysterious monster is sighted in a lake on Mouse Island, Geronimo is called in to investigate! But can he figure out this creature’s secret? PLUS cheesy jokes galore! Praise for Geronimo Stilton’s books: “Lightning pace and full-color design will hook kids in a flash.” —Publishers Weekly

A thrilling cyber-doomsday action/adventure novel that's Ally Carter meets GAMER ARMY. Ada Genet's father, Remy Genet, was one of the most infamous criminals in the world, specializing in infiltration, theft, and cybercrime. As far back as she can remember, Ada had been his accomplice. She helped him steal secrets from governments, weapons from terrorists, and money from just about everyone. But when the law finally caught up with them, Remy ended up in prison -- and Ada at a military boarding school, as a ward of the US Government. Now something called the Hacker's Key has been stolen from a secret UN installation. The Key could supposedly shut down every computer, smartphone, and internet-connected device simultaneously, causing mass chaos around the world. A Techno-Doomsday. A clue left behind at the scene points to Ada's father, but he's been in prison the whole time. Then Remy springs one last surprise. He'll speak, but only to one person -- his daughter, Ada.

The Thea Sisters are on a magical adventure! The Thea Sisters' next adventure to the Kingdom of the Fairies!

Holey cheese! Join Geronimo as he returns to the Kingdom of Fantasy for a third amazing adventure!In this 320-page, full-color hardcover adventure, Geronimo returns to the Kingdom of Fantasy when he learns that the Kingdom has fallen under an endless, freezing winter and the Queen of the Fairies is in danger. Once there, Geronimo explores fantastical new lands and travels on a magical talking ship. Can Geronimo extinguish a threatening volcano in time to restore peace and springtime to the Kingdom of Fantasy? He is put to the test on this extraordinary quest!