The more of these 39 Clues I read, the more I doubt that the end will be worth it. My son loved these books and they're not bad for kids, but there is just not enough substance to keep my interest. In this book #5, we get more of the same - an 11 & 14 year old somehow capable of world travel, dangerous adventure, and finding lost historical secrets all on their own. Amy & Dan travel to Russia which comes across very "Cold War-ish." KGB protected secrets and that sort of thing abound in this novel. I like that the kids are taught a little of Russian history including the execution of the Romanovs, though the book takes a little bit of literary license with this story. And again, we only get one more clue. At some point Amy & Dan are going to have to find about 10 of them at once in order for this to get wrapped up! Maybe just leave this series to the kids, I'm going to pick up a more "adult" book next.