The Killing Curse — H.B. Moore

Omar Zagouri should have known that the hunt for an ordinary art thief in London would end up being far from ordinary. Abducted and carted across several countries until he's locked up in the middle of Jordan's desert, Omar becomes the target of an underground crime organization that dates back to the Crusaders era. As Omar works to uncover the deadly secrets that connect centuries of deceit, he finds himself trying to prevent an honor killing from turning into another tragedy, while exposing the ancient crime organization for generations of lethal corruption.