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...

While on a mission to prove to Merlin that they can use magic wisely, Jack and Annie travel to seventeenth-century Venice, Italy, to save the city from disaster.

Who wouldn't want to live in a treehouse? Especially a 13-story treehouse that has a bowling alley, a see-through swimming pool, a tank full of sharks, a library full of comics, a secret underground laboratory, a games room, self-making beds, vines you can swing on, a vegetable vaporiser and a marshmallow machine that follows you around and automatically shoots your favourite flavoured marshmallows into your mouth whenever it discerns you're hungry....

Their magic tree house takes Jack and Annie back to retrieve a lost story in ancient Greece, where they witness the original Olympic games and are surprised to find what girls of the time were not allowed to do.

Fifth-grader Winnie, with notes from her friends, writes of turning her treehouse into an embassy after her newly-divorced parents become unreasonable, where she is joined by nine others with complaints.

The magic tree house takes Jack and Annie to Africa where they meet up with wonderful wild animals, a very hungry warrior, and where they even solve a riddle.

Froggy and his friends build a treehouse, while avoiding help from his little sister, Pollywogilina.

Andy and Terry live in a 130-story treehouse. It used to be a 117-story treehouse, but they added another 13 stories. It has a soap bubble blaster, a time-wasting level, a 13-story igloo, the GRABINATOR (it can grab anything from anywhere at any time). It is a toilet paper factory, and an extraterrestrial observation center for observing aliens. As it turns out, though, it's Andy, Terry, and Jill who are being observed and then abducted by a giant...

A castle looms dark against the light of the moon. No candles burn in its windows. No laughter rings through its halls. What has happened to the castle and the people who lived there? Merlin the magician asks Jack and Annie to find out. But are they brave enough to step through the creeking doors and solve the mystery of how the castle became haunted?

Wanting a place of his own with fewer rules, Curious George decides to build a tree house but finds the task more challenging than anticipated.