This was one of the most wonderfully complicated novels I've ever read, which is entirely down to the setting. The combination of detective noir with this really interesting dual city and the way the city influences the way the crime is committed is very skillfully done. The plot starts out a bit slow, but it picks up momentum until by the last third it's at a full-out sprint as Borlu figures out the mystery and navigates the cities. I'm a fan of good worldbuilding, and this is some of the best I've seen.