I've gotta say that I'm pretty much been enthralled with this world of lawmen and bikers that KA has created in this series and the follow-up Chaos series. They've been great reads when I need something with action and romance. 
 While Mystery Man was enjoyable, it had some problems that made me glad that I read other books in this series first, because I might not have continued on just on the basis of this book alone. Gwen has been sharing her bed with a "mystery man" that she met a restaurant. He comes to her bed, unannounced, sleeps with her and then disappears. When Gwen's sister gets in some major trouble, Gwen finds out just who she has been sleeping with. 
 Hawk comes and goes as he pleases. He's all alpha, and what I did like about Mystery Man is learning more about the connections between Hawk, the cops, Mitch and Brock, and Tack and Chaos. Having read Motorcycle Man already, it was nice to fill in the background between Gwen and Tack. 
 That leads into two problems I had with this story. First off, Gwen goes from having to resort to an unknown man in her bed, to having 3, yes 3, hot guys lusting after her openly. While I did find Tack's persistence endearing, it just seemed over the top that there were 3 guys after her. 
 What bothered me most was Hawk's treatment of Gwen. He basically dumps her, and I mean he dumps her after one of the worst days she's had since she's been involved with her sister's problems. He's cold and cruel about it too. Then he expects her to just forgive and forget that because he explains it to her later, and when she doesn't, accuses her of not being compassionate. Granted, he has a big piece of baggage he carries around, but still, that was a disturbing sequence in the book. 
 So, overall a solid 3 for me. Loved learning a little more about Tack and the Chaos gang.