Mary Pope Osborne

Their magic tree house takes Jack and Annie back to a monastery in medieval Ireland, where they try to retrieve a lost book while being menaced by Viking raiders.

Jack and Annie are whisked back in time to Old Philadelphia by the magic tree house to meet the Founding Father, journalist, and famous inventor Benjamin Franklin.

The magic tree house is back with a message from Morgan le Fay telling Jack and Annie to seek out "The Gray Ghost" and listen to her story, and immediately they are whisked away to Nepal where they meet Tenzin, a climber who has recently lost his family, and who takes them up the mountain to meet a snow leopard and renew himself.

Jack and Annie travel in their magic tree house to the land of the mystical selkies to seek a magical sword for Merlin.

Jack and Annie travel in their magic tree house to Elizabethan London, where they become actors in a production of A Midsummer Night's Dream and try to rescue a tame bear.

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.

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

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.

"Join Jack and Annie as they as they meet one of the world's most famous illusionists - Harry Houdini!"--

"When the magic tree house whisks Jack and Annie back in time, they land in the tallest tree in Yosemite, California where they join nature conservationist, John Muir, and US President Teddy Roosevelt on a historic trip through the woods"--