This is a good mix of steampunk/western with some supernatural thrown in for good measure. A war rages on the West between the Line (steampunk) and the Gun (western) parts. Only one person possesses knowledge on how to stop it, but there is a minor problem - his mind is almost completely destroyed. Now both sides try to get a hold of this dangerous knowledge.
The only part I am unclear on - is this supposed to be a standalone? If so, the author makes a really good job of building a unique world in just one book.