The Walled City by Ryan Graudin (2014)
here if you want to see what it looked like.) Ryan Graudin used the real city as inspiration for the setting in her young adult novel, The Walled City.
The city of Hak Nam is rough and gritty and dangerous. The only rule of law is maintained by an organization called the Brotherhood of the Dragon, which is presided over by a man called Longwai. Longwai is also a drug trafficker and runs a brothel and it is through these avenues that he is connected to the main characters of the novel.
The story centers on three desperate teenagers who have all been trapped in the city for a couple of years. Jin Ling lives on the streets disguised as a boy so she won't be sold into prostitution like the sister she came to the city to search for. Mei Yee is confined to a brothel with seemingly no escape. She is well fed and cared for, but at a very high price. Finally, Dai is haunted by a mysterious past and has an opportunity to get out of the city, but time is running short and he needs help. All three have become streetwise and untrusting and have taught themselves how to survive in this unfriendly place.
This book just came out in November and I heard very little about it, but ever since my vacation to Hong Kong it's hard to resist any book set there. I found the story and characters compelling from the very beginning, the story fast-paced and exciting. Also it made me want to go to Chinatown and eat all the things. Even though the characters were often starving, when they had food I could almost smell it and it made me very hungry! The food was just part of the local atmosphere, which I thought was very well evoked, and the setting was definitely a huge part of the story. I kept rooting for Jin, Mei Yee, and Dai from the time I met them until the final, satisfying conclusion. If you're looking for a change from YA books featuring white kids in boarding school (as much as I love those stories!) I highly recommend this unusual, refreshing novel.