I received this book through goodreads giveways.Honestly, this book is brilliant. Recommended for fans of alternate history, dystopia, and just plain science fiction. A war is raging in the old American West between Agents of the Gun, people who allowed spirits of demons to ride them, and The Line, who march to the Song of the Engines, who threaten to take over the entire known world. The story follows John Creedmoor, an Agent of the Gun, and Liv Alverhyusen, a psychologist who travels to the West to heal victims of The Line's Noisemakers--a fearsome bomb that breaks the minds of it's victims and drives them mad. It's an epic adventure, across the known East to the wild, untamed forests of the West.I'm especially fond of the character of Creedmoor, a reluctant antihero, who joined the Gun in his youth. Now old, but not breaking down due to his pact with the demon Marmion, he seems to perhaps regret his choice to be in service of his masters, and across his travels, he's at war with himself, his thoughts bringing punishment from his masters. He seeks any opportunity to disobey them.