Mary Pope Osborne

Their magic tree house takes Annie and Jack to Pompeii just as Vesuvius is about to erupt, and they must find a Roman scroll before everything is covered with burning ash.

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.

The first Magic Tree House® Super Edition—and Jack and Annie’s most dangerous mission ever in the scariest time the world has ever known—World War II. With a longer story and additional facts and photographs, this is a thrilling adventure no reader will want to miss!
 
When the magic tree house takes Jack and Annie back to World War II, Europe is in trouble! It is June 1944 and the brother-and-sister...

Jack and Annie travel in their magic tree house to the land of the mystical selkies to seek a magical sword for Merlin.

Jack and Annie travel back to Victorian London when Merlin asks them to use their magic to inspire Charles Dickens to write "A Christmas Carol."

Guided by a magic rhyme, Jack and Annie travel to ancient Baghdad on a mission to help the Caliph disseminate wisdom to the world.

The magic tree house takes Jack and Annie to Antarctica to search for the fourth secret of happiness for Merlin.

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 visit the Paris World's Fair of 1889 in an effort to protect four scientific pioneers from an evil sorcerer.

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...