Jade City and Jade War are excellent, tightly-written gangster stories set within a fantastic world.
The setting is easy to summarize. Janloon is an Asian-flavored fantasy city on the small island of Kekon, which in recent history won its independence from the fantasy China look-alike. The heroes who helped free it formed clans, which each have their own territory within Janloon. Two chief clans exercise this duopoly on violence using jade, which gives people with Kekonese ancestry somewhat superheroic powers.
But now the old leaders of the clans are dying. Foreign drugs are allowing non-Kekonese to use jade. So we follow Hilo, Lan, and Shae as they try to adapt to this world, and keep the No Peak clan from being destroyed by the Mountain clan.
I'm not sure how much the parts I really liked in it are due to the author's excellence, and how much they are due to my not having really read gangster fiction.
So, for instance, I loved the characterization of one of the main characters, Hilo.
In the first book, he was the kind of person I would normally dislike; his moral system is based around particular loyalties to family and almost nothing else, just like Trump. And when the book opens, I did dislike him. But, by the end of the book, you cannot help liking him for how he tries to help people within his clan, according to these particular loyalties. I think the author said that she wanted to write a novel around people who would be, from most other perspectives, villains, and she succeeds at this brilliantly.
Of course, in the second book, he continues to live according to his lights, and inevitably becomes more hard to like. Even so, the characterization remains good throughout.
The plotting is tight, the action scenes are fast, and anyone can die. Overall, I recommend it if you want to have a feel for the attraction of the kind of non-universalist ethicalist systems that most people throughout history have actually followed.