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.

Their magic tree house takes Jack and Annie deep into the sea, where they meet up with dolphins, sharks, and octopi as they search for the answer to an ancient riddle.

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.

Jack and Annie continue their quest for the secrets of happiness, secrets they need to save Merlin. This time, the Magic Tree House takes them to the one continent they haven't visited before: Antarctica! What can they hope to learn about happiness in such a barren place? Only the penguins know for sure but Jack and Annie are about to find out!

Abby's first problem is that Jonah has lost all his memories of the magic mirror and their adventures, so when they get sucked through into Beauty and the Beast, he is unaware of the danger, and picks one of the Beast's roses--her second problem is locating Beauty and performing a match-making miracle in order to recover her brother, and still make it back to the real world before their parents miss them.

Hermione and Ron convince Harry to secretly train students for the wizarding war and Dumbledore is intent upon preparing Harry for the approaching battle with Lord Voldemort.