** spoiler alert ** 
 Once again, we are thrust into the amazing world of Luce, Daniel, Cam, and all the other fallen angels. This book was simply amazing. I thought it was a fantastic conclusion to the series. Lauren Kate has never failed to disappoint me in this series. The descriptions were well-thought, and well-described (view spoiler)[(I especially loved the descriptions of Heaven) (hide spoiler)]. They came alive to the reader, and you felt as if you were right there with Luce and Daniel, experiencing the same ups and downs as they were. You wanted them to succeed against Lucifer, and right everything. I was caught up in the rush, and just as the characters felt the nine days passed too quickly, I too felt the book wasn't long enough. This book never dragged, and was action packed. I finished this in 1 sitting, and kept wishing it would never end. 
 All of the characters were wonderful in this book. I love Arianne and all of her comments, and I especially loved Dee. However, as I mention later in my review, I felt Cam took a back seat in this novel, whereas the other fallen angels that were not mentioned as much in the other books, were front and center. I didn't like this that much, but I'll save my little rant for later. 
 I knew something was different with Lucifer, and knew there had to be some reason he was so focused on Luce. However, I didn't guess that they used to be together. I thought this was a very good twist, however. I did figure out that Luce was ultimately going to be the deciding figure in the whole thing. I knew she was going to be an angel, so I simply assumed that she was the one who had to make the decision. I'm also going to assume that per the epilogue, we are to believe that Lucifer is mortal(cue boy in the laundry room). In a way, I have to wonder if this is truly going to be the last book or if there is going to be a spin-off because of some open-ended things. 
 Despite all of the wonderful compliments I have with this book, I only have one complaint. Cam. Why was there no ending for Cam? For that matter, why was there hardly any Cam in the book? I mean, he was a main character for the first 3 novels, and then in this one, he was basically absent for the entire story, except for choice parts. Even though I have always loved Daniel, I also have always had a soft spot for Cam. I can't fully remember if we found out who broke Cam's heart, originally, so I would have liked Ms. Kate to reinforce this, but that I can get over. What I can't get over, however, is that fact that we have no clue as to what happened to Cam. There is a hint of something in the Epilogue, when Shelby says, "Do you ever see Cam?" and then everyone becomes quiet, but what in the world does this mean? Does this mean that Cam is dead (hopefully this is not true), does this mean that Cam just doesn't want to see anyone, or possibly is Cam even mortal somehow? I really hope that Ms. Kate is planning a spin-off, or even a short novella to tell all of us fans what Cam is up to, because I NEED TO KNOW!!! 
 I highly recommend this book to anyone who has read the previous 3 books in the series because you do not want to miss this thrilling conclusion. I also recommend this entire series to someone who is looking for a great book with angels as the theme. In a time where there are so many angel/vampire/werwolf/fairy books, this is one angel series that is incredibly well written, and never disappoints. This is one series that I loved getting caught up in, and will miss it dearly. Hopefully, there is some continuation in the series in the form of either a spin-off or novella, but I also eagerly await the next book that Lauren Kate decides to write.