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.

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.

"Jack and Annie use the magic tree house to travel back in time to 1947 Brooklyn, New York, where they pretend to be batboys at Jackie Robinson's first game with the Brooklyn Dodgers against the Boston Braves"--

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."

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

Jack and Annie travel back to nineteenth-century Ireland to inspire a young Augusta Gregory to share her love of Irish legends and folktales with the world.

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

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

Introduces the Vikings, discussing why they went on raids, what they wore, what their ships were like, and how they shaped history.