4.5 stars 
 This may be my favorite of the Sin Brothers books. Granted, Total Surrender isn't out yet, but Nate and Audrey kept me on the edge of my seat, turning pages as fast as I could more than either of the other two books in the series so far. 
 Nate had his heart crushed by one person just before he and his brothers made their escape almost 5 years ago. When it becomes clear that Audrey is the next step in the search for the codes to save his and his brothers' lives, Nate searches her out while hoping he can keep his emotions in check while he finds the answers he needs. 
 Audrey is smart and strong, but is still tied to the commander through her mother. All her life she has wanted her mother to love her. Everything she has done has been to gain her mother's approval and though she still hasn't felt that approval, she holds out hope that one day her mother will come around. Running into Nate again wasn't in her plans though, especially after the way she left things so long ago. 
 There were so many twists and turns that I found this book far less predictable than the previous book. With more appearances by the commander and Audrey's mother, in addition to the plans Audrey is working on, and Nate's own search there was so much more suspense and tension than before as well. All parties who were part of the experiments when Nate and his brothers were boys know that the clock is running down, and as diabolical as the commander has been made out to be in the past, his scheming has only gotten more devious. 
 There were some unexpected elements that made this one both more tense and more emotional. Nate and Audrey had more at stake than a shared history and need to protect each other. 
 I love these brothers and all their women. The lengths they go to in order to protect each other and remind themselves they are not alone are truly heartwarming and only strengthen the familial nature of parts of this story. 
 I can't wait for Total Surrender! What we've learned along the way, the fourth book is sure to be a doozy. 
 I was gifted a copy in exchange for an honest review.