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 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"--

"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"--

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.

"The magic tree house whisks Jack and Annie to Africa where they must use magic to save a rhino and her baby from poachers"--

"The magic tree house whisks Jack and Annie back in time to meet famed Roman emperor Marcus Aurelius!"--

The magic tree house transports Jack and Annie on a mission to the Ice Age where they encounter Cro-Magnons, cave bears, sabertooth tigers, and woolly mammoths.

"Jack and Annie are whisked away to Mongolia to meet the near-extinct little horses and their caretakers, but can they help protect the last of the horses from predators?"--

Jack and Annie travel in their Magic Tree House back to a Hawaiian island of long ago where they make friends, learn how to surf, and encounter a tsunami.

Eight-year-old Jack and his younger sister Annie use the magic treehouse to travel back to the Middle Ages, where they explore a castle and are helped by a mysterious knight.