Discovering that the turtles on Turtle Island have gone missing, the Thea Sisters spot environment-threatening drums of a strange oil and struggle to gather help before spotting a pair of turtles entering a mysterious underground cave.

The Thea Sisters are off to save the rainforest in Malaysia!

"The Thea Sisters help their friend Beatrice prepare for the Summer Olympics!"--Publisher's description.

"Everyone is talking about Windy Island's new surf center, even Nicky's hero, Australian surf champion Gary Moon! The artifical reef is supposed to create perfect waves. But the Thea Sisters have discovered a dangerous secret: even a surf champion can't face these giant waves! It's up to them to break the story before another reef is built off the shore of their beloved Donkey Beach."--Page 4 of cover.

The Thea Sisters are just about to head off on their separate family vacations when they receive a call from Will Mystery. Once again, there is trouble in one of the imaginary kingdoms! A crack has been discovered in one of the maps in the Hall of Roses. The girls head to the Crystal Kingdom to help uncover the mystery. There, they find that a dragon has been wreaking havoc all over the kingdom. He has been turning all of their precious gems into...

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.

Attending an art class in the Netherlands, Violet journeys through the flower gardens, windmills and canals of Holland to investigate the untimely disappearance of her friend's father, a renowned botanist whose absence is linked to a rare black tulip.