This book far exceeded my expectations. The premise of getting lost in the Paris catacombs scarred me quite a bit. Once I realized this is a YA novel I was not expecting it to hit the mark. However, it went there in many ways. I appreciate the dual timeline of what's happening to the girls below the surface and what's happening above ground with the search to find these girls. I like how it does the Buffy the Vampire Slayer thing of mixing real life, coming of age demons with actual scary things such as getting lost in the catacombs and actual murdery bad guys.