An interesting enough story, I suppose. Seemed original enough, the characters and magical creatures, I mean. Solid enough mystery. I didn't realize this was a prequel, though, until I read the afterward. It's listed as the first book on GoodReads.
The interaction between Thierry and Shaw was kind of icky. Even if just look at it as two people, removing magic and stuff, it was icky. What with Shaw being first, Thierry's instructor at the Marshall school, then later her trainer when she is made a Marshall and is . . um . . trained on the job. So, even just having it as two humans, their erotic interaction is icky. Then you toss in that Shaw is an Incubus, with a sexual lure, which he uses a little more freely than you might hope and . . . eww.
Two things with the ending I disliked, well, three but I'll leave the third out. First is part of the story, second might have been out of the authors control. The story ends on something of a cliff-hanger, in that a Magistrate arrives and assigns Thierry and Shaw a case. They must leave now. So they do. And get on a plane. And are headed to Maine. And book ends. Whatever was going on there is not continued in this specific book, nor in the next (as far as I know, I've not completed the second book yet). It's just . . . left hanging. That might be easier to take, probably not, but maybe if I hadn't been at 80% of the book at that point. Or the file on my Kindle. As far as I could tell, I was about to enter a third arc in the book. Then . . book was over. Done. Completed. At 80%. Which is the second issue. The book ending at 80%. There's an afterward then something about the author, but everything after 86% isn't even connected to the Black Dog series, or to this specific author. It's a 'if you liked this book, maybe you'll like this snippet from a completely different series by a different author' thingie.