Mercy is a walker, she is not really a shifter she can just change her shape at will and it's completely painless for her, unlike for werewolves. She has grown up in a world where she is told she is bottom of the pack, lower than low. All due to the fact that the werewolves she lived with thought they were better than a walker, they thought her weak. However when a new were turns up at her garage, she involves herself in the world she's been trying to avoid. Lots of action, a bit of drama and a whole lot of ass-kicking is involved. 
 I really enjoyed this book, Mercy was awesome, Adam became kind of cool towards the end, the whole Samuel thing was interesting, i loved Warren. I could just go on about most of the characters The character development was really well done which really allowed you to understand the characters, and you could tell that every part had a backstory, even if it wasn't revealed quite yet. 
 The plot flowed effortlessly, i finished the book in one sitting, you were kept on the edge of yours toes wondering what was happening and you just couldn't put the book down until finished. The only negative thing i currently have to say is that whilst i enjoyed the book and the plot, it did seem to drag on a bit. I wouldn't have wanted any of it cut, however i found myself looking at the clock before persevering. That being said it didn't stop me from reading the book from cover to cover in just over 3 hours. I would highly recommend this book to anyone interested in the whole `shifter' genre