Mary Pope Osborne

"When Jack and Annie receive an invitation to spend Christmas Eve in Camelot--a magical place that exists only in myth and fantasy--they know they are in for their biggest adventure yet. What they don't know is that the invitation will send them on a quest to save Camelot. Can they succeed even though Camelot's greatest knights have failed?"--Amazon.com.

The magic tree house transports Jack and Annie to the deck of the Titanic to find a mysterious gift that will free a small dog from a magic spell.

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 500 years back in time to Florence, Italy, and spend a day helping Leonardo da Vinci in the hope of learning another secret of happiness.

The magic tree house takes Jack and Annie to Antarctica to search for the fourth secret of happiness for Merlin.

Eight-year-old Jack, his seven-year-old sister, Annie, and Peanut the mouse ride in a tree house to the Amazon rain forests, where they encounter giant ants, flesh-eating piranhas, hungry crocodiles, and wild jaguars.

This time, meet famous explorer Leif Erikson and help save a narwhal! When the magic tree house whisks Jack and Annie to Greenland, they're not sure what time they've landed in, but they immediately know what their mission is: save a narwhal! Then, they meet a young hunter named Leif Erikson, and they ask for his help. But Leif has other ideas.

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."

"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"--

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