This book could be classified in any number of ways. There are elements of fantasy, mystery, suspense, romance, and history. As such, I thought it worked best as an historical novel, because this was the strongest part of the book. The story of Alais and Guilhem and Sajhe was the most interesting part of the book: The unfolding world of Alais in the 13th century was fascinating as we saw the Crusades from a European point of view--as the start of the Inquisition.
The modern parts of the story I enjoyed less well. The fantastical elements felt obvious. The mystery was okay but not great, and I wondered why it unfolded so slowly. The pace was such that it took me a couple of months to get into the book; I'd read a couple pages at night before I went to sleep, but when it was time to sit and relax and read I'd reach for something else. I was interested in what was going to happen, but I didn't have an urgency to discover where the story was going until the book was almost halfway over.
NOTE: The remainder of this review contains some minor spoilers. Summary: Meh.
For me the major weakness of the story was the bad guys (or women as the case may be) . In the historical part of the story I could partially understand why the characters were acting as they did, because everyone was to some degree constrained by their place in society. Oriane had a limited sphere of influence from which she could act, and so her actions were understandable within that context.
The modern villains, however, did not make much sense to me. I did not understand why Marie-Cecile and her son and Authie acted as they did. Their actions were clear, but their reasons for acting as they did made little sense. It felt as if wealth = sense of entitlement = villain and that was good enough. It wasn't. I can understand their desire to collect the items in the Labyrinth trilogy, but I cannot understand their willingness to takes actions illegal and immoral to further their goal.
As far as the romantic portions of the story, I thought this too worked much better in the historical portion of the tale than in the modern half of the book. The relationship between Alais and and Guilhem was complex and developed throughout the story. The relationship between Alice and WIlliam seemed little more than inevitable. Yawn.
Essentially, if the author had spent as much time on the modern portion of the story as she did on the historical portion of the story, this would have been a much stronger book. As it is, I can only recommend it for the historical portion of the book. Half a book is better than none, but there are other books out there where the story remains strong throughout the book that are more worth your time and money.