Magically transported to southwest China to find the final object needed to break the spell on the wizard Merlin's beloved penguin, Jack and Annie take a side trip to the world's largest giant panda reserve.

Merlin the magician will not eat or sleep or speak to anyone. The enchantress Morgan asks young Jack and Annie of Frog Creek, Pennsylvania for help. Jack and Annie know they have to search for one of the four secrets of happiness to help Merlin the magician find joy in his life again. And so they head off in the magic tree house for Florence, Italy, in the early 1500s, then to a misty island in the middle of nowhere, then to the continent of Antarctica....

Carnival at candlelight: Merlin has asked Jack and Annie to help on another Merlin Mission. This time they head back into history to Venice, Italy, in the 1700s. With the help of some new friends, a research book, and a mysterious rhyme from Merlin, the heroes will save the beautiful city from a flood! Season of the sandstorms: Armed only with a research book and a book of magic rhymes, Jack and Annie to back 1,200 years to the Golden Age of...