It was fun to read about the Cathars, heretics who were the object of the only crusade undertaken by the church against fellow Christians. Assuming the book accurately portrays the history, it was actually a war to acquire land, a very believable proposition. The twin plots, set 800 years apart, were too overly connected for comfort and were pretty foolish. But on the other hand, I did read it voraciously. I didn't like the shell games played with the precious ancient books or the scary threatening moments for the main characters, silly attempts to get your blood pumping.