3.5 stars. 
 I liked this a bit less than the first book, but I'm taking off a whole half-star because that ending was too abrupt. I was turning the page ready for the next chapter only to find end-of-the-book filler/bonus material. I actually flipped back and forth a couple of times in confusion, thinking I'd missed something. 
 So yeah. I was not a fan of that. The rest of the book was fun, but I wasn't quite as enamoured with it as I was the first book. Don't get me wrong, this installment is action-packed and the stakes are high, but it just didn't quite have the same charm as the first book did. 
 I'm still interested enough to keep reading, but I really want to know more about the obvious secrets of the Library more than I necessarily want another caper-style story. So we'll see.