The 39 Clues Series
We really enjoyed the first 9 books in the 39 Clues series. After that, the 6-book Cahills vs. Vespers followed by the four-book series, the other four-book series, and the other loose books... let me just recommend that you don't approach this series with a competionist-mindset.
This sounds similar to Magic Tree House but for older kids. My son would love this!

on our list of...

As an Amazon Associate, Upparent may earn commission from qualifying purchases from