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.

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 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.

The magic tree house carries Jack and Annie to New York City in 1938 on a mission to rescue the last unicorn. In this exciting new Merlin Mission, Jack and Annie go back in time to New York City, during one of the darkest periods in the city's history--the Great Depression. Even worse, the city is in the grip of a terrible snowstorm. To stop the blizzard, Jack and Annie must save the unicorn made famous in the Cloister's medieval tapestries. But will...

In their magic tree house, 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.

Is this town haunted? That's what Jack and Annie wonder when the magic tree house whisks them to the Wild West. Soon they run into horse thieves, rattlesnakes, a cowboy named Slim ... and maybe even a ghost! Can they solve the riddle that lets them get along home?

Jack and Annie travel to a monastery in the Swiss Alps where, with the help of St. Bernard dogs and magic, they seek the second of four special objects necessary to break the spell on the wizard Merlin's beloved penguin, Penny.

The magic tree house whisks Jack and Annie to India during the Mogul Empire in the 1600s to search for an emerald needed to break a magic spell.

Jack and Annie travel back to Victorian London when Merlin asks them to use their magic to inspire Charles Dickens to write "A Christmas Carol."