A Scream of Angels. Templar Chronicles, #2

Evil walks the halls of Eden.Necromancers, revenants, even a summoned demon or two - they're all in a day's work for the men of the Echo Team and their enigmatic leader, Cade Williams. But nothing could prepare them for the fury they are about to face.When a Jesuit priest wanders out of the New Mexico desert, telling wild stories about a secret research installation and bloodthirsty demons hunting through its halls, the Echo Team is called in to deal with the situation.
Their orders - investigate the facility, determine exactly what happened there, and deal with any infernal presence that might exist. But the being they encounter there beneath the desert sands has found a way to break the bonds of Hell itself and doesn't plan on going back easily. This time, their foe might prove to be too much for even the best the Templars have to offer.