"Thea Stilton and the Thea Sisters are needed to help Aquamarina, the magical land of the ocean! The enchanted Music of the Sea has stopped playing, and no one knows why. If it doesn't return soon, the realm will perish! The mouselets and their friend Will Mystery travel to the underwater world to find the magical music. On their mission, they swim through dangerous waters, encounter strange and fantastical creatures, and even reveal an ancient mystery....

The Thea Sisters are five students at Mouseford Academy on Whale Island. They are adventurous, lively, fun mice and they want to become journalists someday. Between lessons and friendship, life at Mouseford Academy is incredibly fabumouse!

The Thea Sisters are summoned to the Seven Roses Unit by Will Mystery, but when they get there Will is missing; the sisters follow a trail of clues to the Fantasy Kingdoms, and find out that the Mayhem Mirror has been disturbed, and a terrible curse is about to be unleashed on the Fantasy Kingdoms, and it will be up to them to find the eight Harmonies which can break the curse and save the Kingdoms.

The famous Prince Nogouda pays a visit to New Mouse City and ace reporter Geronimo Stilton has an exclusive interview. Meanwhile, at the Mouse Museum, the rare breed of Shufongfong lizards have been kidnapped! Could like Prince and his kingdom in the Bandel jungle have anything to do with this? Geronimo, Thea, Trap, and Benjamin are on the case!

When, in the process of testing his newest time machine, Professor von Volt accidently brings a triceratops, Helen of Troy, Attila the Hun, Charlemagne, and Christopher Columbus to present day New Mouse City, it is up to Geronimo and his friends to return them all to their own times and places--without being eaten by a T-Rex or skewered by Trojan warriors.

Using the clues found in Aurora Beatrix Lane's travel diary, the Thea Sisters continue their search for the seven lost treasures; and the object this time is the Ring of Eternal Love, a journey that begins in Verona, Italy, with the story of Romeo and Juliet and takes them around the world.

While visiting a filmmaker friend on the set of a new movie with Thea, Benjamin, and Pandora, reporter Geronimo Stilton investigates mysterious accidents that are plaguing production and causing the film to go off course.

"Geronimo and friends have to get to the bottom of a crown jewel of a case! Checkmate, cheese-lovers, er, we mean chess-lovers. For once, all is quiet in New Mouse City, so Geronimo Stilton, Editor-in-Chief of The Rodents Gazette can report on an incredible chess match-up. On one side, Gary Goudov, world-renowned chess champion, and on the other side, a super chess-playing computer! But after Geronimo leaves, the infamouse Gem Gang commits a string...

Once again Geronimo is summoned to the Kingdom of Fantasy, and this time he must rescue five princesses of The Kingdom of Lotus Flowers who have been kidnapped by a terrible witch--but first he must journey to the Island of Dragons to find the bravest, the wisest, the silliest, and wittiest, and the most sincere dragons who prophecy says will aid him in his mission.