Why, I do believe we have arrived.
Harry Dresden is dealing with the ongoing fallout of the war between the Wizard's White Council and the Vampire's Red Court. A war he started and where he still very much stands at the eye of the storm. The Red Court noble, Ortega is in town with a proposition for Harry. A duel. A duel between Harry and Ortega to the death. If Harry wins Chicago is declared a neutral zone. If he refuses the duel? His friends will be targeted and killed. Faced with this non-choice, Harry is forced to accept the duel against a vampire centuries his senior. But life is never so simple for Harry. Susan is back in town, still dealing with the affects of being infected with Red Court vampirism she must struggle against her urges and her attraction to Harry as well as forward her own agenda and the agenda of the organisation to which she now belongs.
Worst of all, the Denarians are in town. Not just demons, but servants and vessles of the Fallen themselves. They're in town and they seek to acquire the stolen Shroud of Turin and use it in their nefarious plotting (and yes, I got to use the words “nefarious plotting” in a serious sentence. Yes this amuses me) opposed by Michael and his fellow Fists of God, the Knights of the Cross and yet further complicated by John Marcone, crime boss also being involved.
Never simple, but most certainly epic.
I would say this is the book where everything this series has been promising to be has finally got into action. Every book until now seems to have been an introduction paving the way to this book, though Summer Knight was epic in its own right.