I'll be honest and say that I bought this book because I really liked the cover, and I thought "This would look really cool on my bookshelves..." The girl at the check-out counter said "Oh my gosh! This book is SO good. I just started reading the sequel."
And it really is good. The setting is an unnamed European country (which seems very close to Victorian England), and each chapter is told from the viewpoint of the three main characters: Miss Celeste Temple (a former uppity society girl who, after being inexplicably dumped by her fiance, quickly becomes a master sleuth and "Alias" type kick-butt heroine), Cardinal Chang (a hired assassin-turned-good-guy), and Dr. Abelard Svenson (a German private physican to royals who is terrified of heights but is continually faced with a number of steep climbs).
All three characters find out that those closest to them have become involved in a dangerous underground society that is seeking to take over the world using people's dreams. I normally don't like science fiction at all, but this is so engaging that I forgot that it is technically a sci-fi story. In fact, it's very reminiscent of "The Pirates of the Carribbean" films. Seriously. Keira Knightley would be great as Miss Temple.
The book ends on a giant cliffhanger, so of course I immediately went to Barnes and Noble and bought the second volume. We'll see if Dahlquist can keep it up.