Travel with brother-and-sister duo Jack and Annie in their Magic Tree House® — as they proceed to answer questions left for them in a mysterious note signed "–M."
They first wish themselves to an observatory where they meet an astronomer who helps them answer the first few questions on the note. With the help of the astronomer, the Internet, an astronaut, books, and the note's author, Jack and Annie are then taken on a wondrous journey of adventure and learning.
Let this exciting voyage carry you to the planets and far out into the universe where the duo nearly... well, you'll have to find out yourself. The adventure is just beginning!