The number one best-selling book series of all time celebrates 25 years with new covers and a new, easy-to-use numbering system!

The magic tree house leads Jack and Annie to a tiny deserted island in the middle of the ocean. The brother and sister team are soon rescued by a ship of explorers and scientists who are looking for...a sea monster!

Formerly numbered as Magic Tree House Number 39, the title of this book is now Magic Tree House Merlin Mission Number 11: Dark Day in the Deep Sea.

Did you know that there’s a Magic Tree House book for every kid?

• Magic Tree House: Adventures with Jack and Annie, perfect for listeners who are just beginning to listen to audiobooks
• Merlin Missions: More challenging adventures for the experienced listener
• Super Edition: A longer and more dangerous adventure
• Fact Trackers: Nonfiction companions to your favorite Magic Tree House adventures