Thea Stilton and her sisters journey to the land of Minwa, a realm linked to the legends of Japan and wrapped in mysteries and enchantments, to discover why the realm's special lotus flowers are disappearing--and why their diappearance seems to be threatening the whole land.

The underwater kingdom of Aquamarina is in trouble because the enchanted Music of the Sea has stopped playing--so Thea and the Thea Sisters, together with their friend Will Mystery set out on a dangerous mission to find the Sea Violin which will restore color and life to the Kingdom.

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 Thea sisters continue the search for the seven ancient treasures, using the clues found in Aurora Beatrix Lane's travel diary to find a fabulous emerald which once belonged to Cleopatra--a quest that leads them from Moscow, to the Sahara, and finally Bolivia.