by Elizabeth Kostova (2005).
Bargain bin buy so I'd have a beach read when I went on vacation. Turns out I loved this book. I'm a big geek for historical research, monasteries, and really old books, so it's no wonder, really. This book reminded me of A.S. Byatt's Possession, and that's a big compliment. The story drags a bit in the middle, but picks back up again pretty quickly. The end in awesome, in that it subverts what you think the climax will be, and turns everything from a monster-hunting story into a family drama about people who are really lovely and worth being invested in.