Windy Night with Wild Horses — Mary Pope Osborne

The #1 bestselling Magic Tree House series for chapter book readers is ready to whisk you away across the world with Jack and Annie--this time to rescue little horses! Perfect for readers ages 6-9!

The wind started to blow. . . and a new magical journey unfolds when the tree house lands in Mongolia, Jack and Annie can hear the drum beat of horses hoofs. The little horses of Mongolia are returning from near extinction and the kids get to meet the people who take care of them. But the horses are still in danger with wolves nearby. . . Can Jack and Annie protect the last of the little horses? 

Did you know that there's a Magic Tree House book for every kid?
Magic Tree House: Perfect for readers who are just beginning chapter books
Merlin Missions: More challenging adventures for the experienced reader
Fact Trackers: Nonfiction companions to your favorite Magic Tree House adventures
Graphic Novels: Relive the original adventures brought to life with art by Kelly & Nichole Matthews

If you're looking for Merlin Mission #39: Dark Day in the Deep Sea, it was renumbered as Merlin Mission #11 when the series was rebranded in 2017.