I was given this book free of charge through NetGalley.Admittedly, I may not be the best judge of Mercy, simply because it took me so long to finish it. Whether that was the fault of the story or the fact that due to the format I had to read on my computer, I can't say, but nothing about the first half of the story grabbed me enough to make me want to find out what happened next. The plot seemed jumbled and drawn out, and I never really cared for any of the characters. I didn't feel we got to know anyone. We don't ever really know who or what Mercy is, only that she's kind of ruthless and unfeeling until she magically develops a conscious halfway through the book. Ryan is just... singleminded and driven, which is understandable, but why does he believe Mercy and accept what she is without question? Nothing about his character really hooked me, and I don't understand his feelings for her--feelings that magically presented themselves in the last few pages.Mercy--I'm still not sure I understand exactly what she is--is an interesting character with a past and a future that would have been compelling had it not been so hard to figure out. Building mystique is good, but when the reader is given absolutely no lead toward the answer it doesn't inspire intrigue, only confusion.I'm giving this three stars--and the benefit of the doubt. Hopefully when I'm able to get it on my Kindle it will be an easier read and maybe make more sense.