I usually don't do negative reviews, but you know, sometimes you have to. I did read this book all the way through, since I wanted to see what happened.
First of all, this title. It sounds like my realtor describing a new development in the town, not an irresistible yarn about a man battling demons. Why not simply, "The Possessed"? That's what Parshall is talking about. Various characters in this yarn are possessed (temporarily) by demons. Just say that.
Without giving away the ending, this is a tale about a lawyer who finds himself entangled in a series of supernatural murders which have a Christian angle--in this case, wounds on the deceased (several of them) appear to mimic in some way the stabbing of Christ on the cross by a Roman soldier's spear; except, the wounds are probably on the wrong side (which side Christ was stabbed on, is still under discussion).
There are a number of areas where this story doesn't develop much interest or tension. Let's review some of them.
Although the author is a lawyer, this tale has a consistent lack of any legal or procedural traction--such as we might expect in, say, a Grisham novel. No interesting tidbits here on how the legal system works or doesn't work.
Trevor's first wife, Courtney, who dies early in the story, doesn't seem to claim much interest of the lead character, and we only meet her briefly before she dies of an overdose. Since the author treats her so off-handedly, readers can't feel her loss to much either. This undermines the story.
When Trevor is disbarred (I won't go into why), this should be a jarring, personally shattering situation, similar to Mikael Blomkvist's loss of his legal case in the beginning of "Girl with the Dragon Tattoo" (to name a bestseller), but it isn't. Parshall underdescribes this entire scenario.
Later in the book (again, no spoilers on the ending), Parshall develops a friendship with a female detective named Ashley in Manitou, his old town. Although there is a romantic attraction, this relationship proceeds set on "low." Many readers will be disappointed.
There seems to be an authorial pattern here.
Finally, when Trevor comes around to his religious "mission," (Trevor is battling the demons; he has been given a gift to recognize them), the description of this realization is so gradual, the reader almost might miss it. It's also related with few references to scripture--which you might be waiting for, given this topic. This is odd.
I found this work puzzling and underwhelming. However, if you are into fiction or horror with a Christian baseline, you might find this your cup of tea.