Plot-wise, it's pretty straightforward.
The heroine is dragged through much of the story, though when she chooses to run towards it, she really moves. She's a young human beat-patroller in an interspecies and inter-caste legal system. She's deliberately ignorant, stubborn, vengeful, and has a Healing Talent that is incredibly strong and that she puts to use for the poor and ... less-advantaged.
Besides trying to leave behind her beginnings in the lawless slum side of the river, she's also trying to outrun (avoid?) ancient black magic that is infecting her from the inside out.
Her loyalties are quite choice, and they are unfolded to the reader in entertaining conversational and physical exchanges (lots of implied backgrounds there). I enjoyed the understated and implied character descriptions. Sagara allows the reader to gain knowledge about the various races and hierarchies through the main character's eyes rather than get a 3rd party description laid out in a travel guide.
This was definitely a good book, and an enveloping read. I managed to bike 9+ miles at the gym last night because I was too stuck in the book to get off of the exercycle.