Caleb Archer has been many things in his violent and checkered past. Wandering the American West as a Rigger, one of the hard breed of men who stand in the Verge and work the transmission poles atop the new Aether trains, he has seen many things, both beautiful and terrible. But what he finds when he wanders into the little town of Hermosa Springs is the most bizarre and deadliest thing he's ever encountered; a creature with a thirst for blood that is unharmed by any earthly weapon. Suspected at first of being responsible for its first two victims, Caleb must clear his name not only with the law, but also with the people of Hermosa Springs. Aided by holy men and women of three cultures, Caleb discovers that his own dark past has left him uniquely prepared to fight the supernatural terror that seeks to prey on the people of Hermosa Springs. But his past alone is not enough. To fight the terror that walks the wilds of New Mexico, he must endure a trial blood and pain that will change him forever, if he can survive it.