Following up on Prince of Thorns, Mark Lawrence continues the story of Jorg, now king of his own land, and heir to another.
The story line in this book is split between the months following his taking the crown, and 4 years later as his little kingdom is beset by a 6 nation strong army lead by the best man to be emperor. In the same way that Jorg is not a good man, Orrin is his opposite. Just as driven, just as determined, but beloved by the people, and the best hope of the broken empire. Interspersed throughout are the pages of a diary from another character, and memories locked away by Jorg in a magical box. Because of this, I wouldn't recommend reading it while tired, it can be a little confusing switching back and forth.
The difference in tone of the book from the first one is interesting. While Prince of Thorns was a very personel level of evil and brutality, the weight of the crown makes King of Thorns a more mature book, suitable for Jorg's more mature responsibilities. He's still surrounded by his brothers from the first book (at least the ones that survived), as well as new followers, advisors, and a wife! While she isn't the love of his life, she does seem to be a match for him. I don't want to give the impression that Jorg has in some way been redeemed. he is still the evil monster he was, he's now just less selfish about it. Sort of.
King of Thorns also reveals much more of the world of the broken empire, and every tidbit is wonderful fodder for a D&D game. As I mentioned in my review of the previous book, the setting is a post apocalyptic europe. Castles are built out of parking garages and skyscrapers, and the people from before the end of the world were known as "The Builders". Fun little bits of the modern and near future world show up, like guns, and satellite imagery, and every time they do, you pause for a minute and have to reset your brain to remember that this isn't your typical fantasy world.