Lily can no longer be a spy for the light, every demon knows who she is and what is hanging around her neck, the Oris Clef, which gives her the ability to control all of them. However, there are some very powerful demons that will do anything to get Oris Clef, even just chopping off Lily's head to take it. As Lily and Deacon battle the demons who want to kill Lily, they are also on the search for the third key which has the ability to close the portal between earth and the demon world for good.
This book takes place right after the second book ends, there is no gap in time and really time is something that Lily does not have, therefore you really do need to read the two previous books for this series. It is not a stand alone read.
This is my least favorite book in the series, (minus the fact that this is the last book in the series as I have enjoyed it so far), I felt that this book lacked the plot and mystery of the first two books. The way that the plot flowed in this book did not work for me.The book was on a constant rotating theme of try to find the third key but where to look for the third key, maybe here, no here, well maybe there isn't a third key, oh lets go fight some demons. Additionally the villains in this book were not as scary as they were in the first two and there was no surprise aspect in the book, therefore, there was not very much suspense or mystery in the book, as this is the final book in the series I felt that the reader knew what was going to happen.
The saving point of this book is the characters. I have liked the characters throughout all three books especially Lily as she struggles with who she has become, the demon powers that she has obtained (but even those were down played in this book) as well as the decision that must make. She knows that she wants to save the world, but an eternity of torture is one that will put anyone off from making that decision. I think that Lily's hesitation to make this decision is very real, and her hope and belief that there is a third key that will lock and close the gate is a natural progression. I like that Lily has to fight her demon side and the struggle she has with having the Oris Clef around her neck which is forever taunting her to rule and there are times that Lily really considers it, she believes that she will be able to control the demons and save the world that way.
Although this was not the best book in the series, and I think the weakest of the three, I still really enjoyed this series and the first two books make up for this one not being as good as I wanted it to be. This is the only series that I have read by Kenner but based upon this one I would read her other series as well.