"An adventure down under! Moldy mozzarella! A flock of sheep at Nicky's family's Australian ranch was losing all its wool, and no one knew why. Nicky and her friends the Thea Sisters headed to Australia and set off on a tour of the whole country in serch of clues. What happened next turned out to be a truly memorable outback adventure!" -- P. [4] of cover.

The Thea Sisters travel to Italy for a ballet competition and must figure out who is trying to sabotage the contest.

Join Thea Stilton and the Thea Sisters on an adventure packed with mystery and friendship!

While on vacation in Greece, the Thea Sisters make friends with a company of actors. They are rehearsing for a show that's about to open — and Colette ends up standing in for an actress who falls ill! Suddenly, right before the performance, the lead actor goes missing. Can the mouselets find him in time for the show to go on?

Join Thea Stilton and the Thea Sisters on an adventure packed with mystery and friendship!

The Thea Sisters are visiting a friend in sunny California — and she invites them to the set of a movie in Hollywood! The mice love being around famouse and fabumouse directors and actors as they're working. But then an important reel of film is stolen from the studio! Can the Thea Sisters catch the thief and save the movie?

Geronimo's adventurous sister Thea narrates this tale packed with action, mystery, and friendship!In this fabumouse adventure, the Thea Sisters head to Alaska, where they're attending a conference held by an important ecological association. Their host and his family are native Alaskans who show the mouselings their favorite games and activities. But soon there's trouble—the Thea Sisters discover that someone is upsetting the ecosystem by blowing...

Join Thea Stilton and the Thea Sisters on this adventure packed with mystery and friendship!

The Thea Sisters are visiting friends at a lively festival in Spain. But the theft of a precious fan turns their trip into an investigation! They end up hot on the trail of a secret treasure . . . but they're not the only ones searching for it. Can the mouselets solve the mystery in time? It's a mission full of flamenco dance!

Join Thea Stilton and the Thea Sisters on an adventure packed with mystery and friendship!

While Violet is taking an art class in the Netherlands, her friend's father suddenly disappears! The missing mouse is a renowned botanist — and his disappearance is linked to the mysterious black tulip. The Thea Sisters are eager to help find him. It's an adventure through the flowers gardens and canals of Holland!

Geronimo's adventurous sister Thea is taking the publishing world by storm in this fabumouse tale packed with action, mystery, and friendship.In this exciting adventure, the Thea Sisters are off to Japan on a cultural exchange program. While they're busy exploring Kyoto and admiring the beautiful cherry blossoms, a valuable doll is stolen from a wealthy Japanese collector. Will the five mice be able to track down the doll and catch the thief? Readers...

What is the secret of the clouds?

The Thea Sisters have received an urgent message from their friend Will Mystery. The magical Land of Clouds is in danger. The mouselets must find out why the clouds are disappearing!Once they enter the kingdom through Mount Everest, the mice meet fairies, elves, and unicorns on their way to the majestic Cloud Castle. But who can the Thea Sisters count on to help solve the mystery? It's an incredible journey...

Geronimo's sister Thea Stilton narrates this action-packed adventure!When the Thea Sisters' friend Bridget returns to Scotland for a family emergency, the five mice offer to help. And when Bridget goes missing, they have to rush to Scotland to help find her! Along the way, the Thea Sisters encounter Celtic legends, cryptic messages, and hidden treasures on a trip that's full of surprises!