This book deals with something that readers never thought they'd see: a look at Satan, who is also the Incarnation of Evil, a point not really touched on previously. The book follows the same pattern as the previous books in the series, where the first part of the book deals with the mortal life of the main character before he becomes the Incarnation, then looks at the events of the other books from the eyes of this particular Incarnation, before culminating in some sort of revelation about this Incarnation.
The idea behind this book is something that we have seen developing for quite some time, the idea that while there is evil in the world, Satan is not strictly evil, but rather the Incarnation that holds sway over evil. In this story, while he is treated as being evil by most of the other Incarnations, he is more like the Greek god Hades, whose domain is the underworld and everything that eventually comes down there. In the same way Satan is the lord of Hell and has dominion over all of the people in Hell. The point that the author tries to make is that one can sympathize with Satan in this format. He shows the main character's very harsh life and the events leading up to him being given the opportunity to take the role of Satan.
Once he takes that role, we are taken into his mind and into his heart and begin to see that he is not really all that bad. He is not interested in sending everybody to hell, but only those who deserve it. As such he is more like a prison warden doing a job that nobody else likes. He is also like the police officer who has a role to perform, but is hated by many because his role tends to bring him into conflict with others.
However, this book is extremely long winded! Perry's life spans so long, with so many historically significant events in it, that I lost interest fairly quickly. The ties to the previous books were interesting, and the end redemption especially so, which saved it from a two star rating. While I think this is one of the weaker books of the series, it is also a somewhat interesting one.