Mary Pope Osborne

"Jack and Annie travel in the magic tree house to Galveston, Texas on September 8, 1900--the day of the worst natural disaster in US history"-- Provided by publisher.

"When a mysterious note invites them to Camelot, Jack and Annie travel in the magic tree house to the magical kingdom where they must find a lost dragon"-- Provided by publisher.

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 are joined by Teddy and Kathleen as they travel to the snowy Land-Behind-the-Clouds, where they search for the eye of the Ice Wizard and attempt to help Merlin and Morgan.

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

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.

As a thank-you from Merlin and Morgan, Jack and Annie are sent on what should be a vacation at a luxurious resort in Cozumel, Mexico, but is, by mistake, an adventure with ancient Mayans, instead.

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.

When Merlin is weighed down by sorrows, Jack and Annie travel back to feudal Japan to learn one of the four secrets of happiness.

Guided by a magic rhyme, Jack and Annie travel to ancient Baghdad on a mission to help the Caliph disseminate wisdom to the world.