This was another well-written book in the series. I really liked learning about Mercy's father and the folkloric backstory. And I enjoyed the surprise near the beginning of the story.
What I didn't enjoy as much was the central mystery, and that this was just a Mercy and Adam story, with very little of the secondary characters that we are used to from the rest of the series. I enjoyed Stefan's reappearance, but wished for more from him and the others.