The magic treehouse takes Jack and Annie to a moon base in the future where they continue to search for the fourth thing they need to free their friend Morgan from the magician's spell.

Eight-year-old Jack and his younger sister Annie find a magic treehouse. Each book in the collection takes them to different places.

Andy and Terry live in a treehouse. But it's not just any old treehouse, it's the most amazing treehouse in the world! This treehouse has thirteen stories, a bowling alley, a see-through swimming pool, a secret underground laboratory, and a marshmallow machine that follows them around and automatically shoots marshmallows into their mouths whenever they are hungry. Life would be perfect for Andy and Terry if it wasn't for the fact that they have to...

Eve of the emperor penguin: The magic tree house takes Jack and Annie to Antarctica to search for the fourth secret of happiness for Merlin. Moonlight on the magic flute: Jack and Annie travel to Vienna, Austria, in 1762 where they meet the young Wolfgang Amadeus Mozart and his sister and help save the budding genius' life.

Jack and Annie join Merlin on a magical mission to King Arthur's castle at Camelot, a haunted castle, fight a giant sea serpent, and travel to the land of snow.

Andy and Terry are once again inviting readers to come hang out with them in their astonishing 39-story treehouse (it used to be 13 stories, then 26 stories, but they keep expanding). And this year they will have even more time to jump on the world's highest trampoline, toast marshmallows in an active volcano, swim in the chocolate waterfall, pet baby dinosaurs, and go head-to-trunk with the Trunkinator, since Terry has created the greatest invention...