Mary Pope Osborne

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...

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 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 look at knights, armor, and life in a castle.

Presents a nonfiction companion book to "Stallion by Starlight," discussing the history of domesticating horses and explaining why Alexander the Great's horse was so famous.

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

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.

Jack and Annie are whisked back in time to Old Philadelphia by the magic tree house to meet the Founding Father, journalist, and famous inventor Benjamin Franklin.

The magic tree house takes Jack and Annie back in time to feudal Japan where the siblings learn about the ways of the Ninja.

Eight-year-old Jack and his younger sister Annie find a magic treehouse, which whisks them back to an ancient time zone where they see live dinosaurs.