The fallen - Eric Lustbader

In a hidden cave in the mountains of Lebanon, a man brings what has been forbidden for thousands of years out of the darkness and into the light: the Testament of Lucifer. In Istanbul, Bravo Shaw, member of a secret Franciscan splinter sect, is unearthing the chronicle of a conflict most ancient: the war between Good and Evil, waged to a standstill since time immemorial. But now Lucifer's advance guard, the Fallen, has arisen. All of humankind is at risk of being enslaved by the forces of evil. Bravo, his ageless confessor Fra Leoni and his blind sister, Emma, are the first and last line of defence against the unleashed chaos. But they may well forfeit far more than just their lives.