Reviewed by E.M. (age 7)
It's a really good book because reading about the dinosaurs was interesting. I also liked that it was a mystery because Jack and Annie don't know how the tree house and the books appeared. They just have a few clues. One of the clues is a gold medallion with an M. They also found a bookmark as a clue. I also enjoyed reading about a brother and sister, because I have a sister too.
I recommend this book for kids in first through fourth grades. If you want to see what happens in this mystery go and get the book!