The Hand of Sin

From publisher blurb:

Residents of the Eastern District whisper of a new threat to Emerald City. They say a remorseless killer stalks the streets and the elders of the community say the man they call Shou Tzin, or the Hand of Sin, bears a resemblance to a powerful figure back in their homelands. So far, only the deaths of a handful of gangsters has been blamed on the stranger, but who is the Hand of Sin really and what does he want?