Blood Infernal (Order of the Sanguines) :
In a masterpiece of supernatural mystery, New York Times bestselling authors James Rollins and Rebecca Cantrell bring The Order of the Sanguines trilogy to its thunderous conclusion in . . . Blood Infernal
As a scourge of murders sweeps the globe, archaeologist Erin Granger must decipher the truth behind a prophecy in the Blood Gospel, a lost tome written by Christ. With the Apocalypse looming, Erin again joins forces with Army sergeant Jordan Stone and Father Rhun Korza to search for the key to mankind's salvation. But the prize has already fallen into the hands of their enemy, a demon before whom even the walls of the Vatican will fall. Erin will discover that the only hope for victory lies in an impossible act--one that will destroy not only her, but all she loves. To protect the world, Erin must walk through the very gates of Hell and face the darkest of enemies: Lucifer himself.