I read a fair amount of historical fiction, which is why I picked up this book. I have always had an interest in the Templars.
The central conceit of this book is that the Knights Templar not only survived the attempted eradication of the 14th century and not only survived, the thrived. Now they are one of those uber-powerful secret organization that operates totally outside the laws of any nation and is bound only by their own honor.
The plot revolves around a 12th century treaty that is signed by two separate popes and three European Kings. This treaty is an agreement that the Christians should eliminate the Muslims if possible. The real rub is that the Second Vatican Council proclaimed that popes are infallible, speaking the true Word of God. If the popes are infallible and popes (even ancient ones) are calling for the death of Muslims, that obviously puts the church in an awkward place.
I suppose the easy comparison would be the blending of imagined history and fiction that Dan Brown did, but I actually liked this better. The plot seemed a little overwrought from time to time, but I loved the characters. Character development is something so often overlooked in this genre, but it was a strength here.
My one nit to pick was that the powerful heads of the Templars spoke in an exceedingly casual way. I believe this was a conscious decision on the part of the author, but it sometimes took me out of the story a bit.
In the end, the book built a nice momentum, and has a very satisfying ending. Personally, I would be interested in reading another book set in this same world.