Mary Pope Osborne

On Christmas Eve, Jack and Annie's tree house transports them to King Arthur's castle at Camelot, where they undertake a quest to the castle of the Otherworld.

In their magic treehouse, Jack and Annie are again transported to King Arthur's realm, where invisible beings, giant ravens, and mistaken magic spells have a duke's castle in an uproar on Halloween night.

Jack and Annie travel in their magic treehouse to the year 1621, where they celebrate the first Thanksgiving with the Pilgrims and Wampanoag Indians in the New Plymouth Colony.

Jack and Annie visit the Paris World's Fair of 1889 in an effort to protect four scientific pioneers from an evil sorcerer.

While on a mission to prove to Merlin that they can use magic wisely, Jack and Annie travel to seventeenth-century Venice, Italy, to save the city from disaster. 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! Yet another...

Their magic tree house takes Jack and Annie back to the Wild West, where they experience excitement and danger and try to solve a riddle.

"Travel to Ancient Greece with Jack and Annie as they meet Alexander the Great and help tame his wild stallion"--

Their magic tree house takes Jack and Annie deep into the sea, where they meet up with dolphins, sharks, and octopi as they search for the answer to an ancient riddle.

When Jack and Annie travel back to the Kansas prairie in search of "something to learn, " they gain an understanding of how hard life was for pioneers and they experience the terror of a tornado.

Their magic tree house takes Jack and Annie to the Arctic, where a polar bear leads them onto very thin ice.