I'd give this 4.5 stars because halfway through the story it got a bit dull for some reason and I lost some interest in the book and characters. But then the action picked up and I remembered why I enjoy this series so much.
One element of surprise (well, other than the obvious twists and turns in the plot line) was the quick glimpses into Adam's point of view. It seemed like the only way to show what was happening to Adam and the pack, while they were held captive by those mercenaries. And I liked it (Adam's inner thoughts, not the pack being kidnapped). I am kind of hoping there might be a book in the future set in the same universe but having a werewolf as the main character. But I digress.
As is always the case with Patricia Briggs the actual culprit is never in the original assumptions. So I spent 3/4 of the book wondering who might be behind the kidnapping and what their agenda was. I got a bit lost in the details when fae, vampires all joined in to search for the pack. I blame my lack of attention on the fact that Mercy wasn't out there on her own kicking ass but had to depend on others (or it felt to me that she had to rely more heavily) in order to get things done.
Then when Adam was finally able to break free, I knew the respite was temporary and more adventures were on the way. I wasn't disappointed. There were some interesting new concepts brought in the story (such as Mercy's ability to suck the silver from Adam through their bond or her eyes turning yellow - I wonder what that was about - or being able to mix both coyote and human self to understand how Frost was using his powers). I loved the final battle(Mrs. Briggs knows how to deliver a climax scene). I was intrigued by this new powerful vampire Thomas Hao, who charmed Mercy with his graceful fighting style (and hope we might meet him again later on, as friend and ally, not enemy).
There are just so many possibilities stemming from the plot of each book, so many allies or enemies that could arise from the multitude of characters being included in this universe. It's one of the things I love about the book, that there is always something to surprise me and leave me wanting more. Can't wait to move on to volume 8.