In their magic treehouse, Jack and Annie are again transported to King Arthur's realm, where invisible beings, giant ravens, and mistaken magic spells have a duke's castle in an uproar on Halloween night.

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.

The magic tree house carries Jack and Annie to New York City in 1938 on a mission to rescue the last unicorn.

Blizzard of the Blue Moon
Jack and Annie are off on another Merlin Mission. This time, Merlin has sent them to rescue a beautiful magical creature–the unicorn. But when they land in New York City during the Depression of the 1930s, Jack and Annie are confused. Where will they find a unicorn in a big city? And what about the blizzard that's burying New York in snow? Can Jack and Annie make their way through the windy streets, find the...

When eight-year-old Jack and his seven-year-old sister, Annie, join a group of nineteenth-century explorers aboard the H.M.S. Challenger, they learn about the ocean, solve the mystery of its fabled sea monster, and gain compassion for their fellow creatures.

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."

Jack and Annie travel back to nineteenth-century Ireland to inspire a young Augusta Gregory to share her love of Irish legends and folktales with the world.