This is an excellent fantasy story with a great setting, a sinuous plot and an outstanding cast. The city of Deepgate is suspended both on great chains over a bottomless abyss and in a war between Heaven and exiled angles who live in the abyss. Dill, last of the battle angles who protected Depgate is about to assume his duties, Rachel, a Temple assassin is assigned to tutor him. The city is haunted by a rouge angel, Carnival, who kills once a month on Scar Night. All three become caught up in a plot started to protect the city but which threatens its final destruction. The reveals smart and fast, the action is superbly staged and the cast busting with life. The twin pillars of the city of chains and the theology that created it and sustain it are developed with great confidence and clever, unexpected detail. Both have numerous surprises in store and they are revealed in a very entertaining fashion. The cast are very much grounded in the physical and supernatural realities of the city and its surroundings, the plot uses the details with relish. The cast are revealed and develop through action, they are constantly in motion with just enough time and information to grapple with the immediate problems and never enough time to think about the bigger problems they have.The shifting narrative means that the reader is just barely ahead of the cast in knowing what is going on, the plot grips tightly, the twists and turns never undermine its credibility. Dill is a little of a blank slate, which given his carefully structured upbringing is unsurprising. Rachel is sharply etched, confident and capable as well as feeling isolated and unsure. The rest of the cast emerge with force and determination as they struggle to shape events that are running ahead of them. This superb fantasy adventure is gripping, thoughtful, constantly surprising and hugely enjoyable, a treat.