I didn't read the first book in this series - I know, my bad - but it really felt like I missed a lot, because this book has so many ties to the first one. I would definitely recommend you to start reading the first book, Retribution, because I felt like I missed a great deal.
The story itself is quite interesting, cops are being killed and it seems like someone knows about a cover-up that has taken place in - you guessed it- the first book. The writing is nice, the book is fast paced and a lot happens. Still, I never really got the feeling that I really was enjoying the story though. It just didn't seem special enough.
Note: I read a Dutch translation of this book