I have no idea why the publishers are calling this science fiction. It's really more of a horror/fantasy blend; the only sci-fi element I can think of is the near-future setting. Which suits me just fine. ;)
The world of _Brown Girl_ is frighteningly plausible--it is the logical conclusion of our current suburban sprawl and consequent urban decay. Here, even the city government has fled to the suburbs, and no one is left in the inner city but the poor. There is no electricity, no sewer system. You can't get into the hospital unless you are wealthy. And Rudy, the diabolical crime boss of Toronto, is selling organs to these hospitals--and let's just say the donors are less than willing.
And in this city lives Ti-Jeanne (Little Jeanne), a new mother, staying with her wise grandmother, Gros-Jeanne (Big Jeanne). Gros-Jeanne wants to pass on her knowledge to Ti-Jeanne, but Ti-Jeanne only grudgingly learns herbal skills, and wants nothing to do with Gros-Jeanne's other talent--the practice of Afro-Caribbean magic. Then one night they hold a ritual to help Ti-Jeanne's deadbeat ex-boyfriend, and the spirits tell Ti-Jeanne that it is her destiny to stop Rudy's evil.
We are sucked in, as Ti-Jeanne's course becomes more irrevocable, as she comes to accept the orishas, and as her ex-boyfriend's fear and drug addiction drive him into worse and worse trouble. Ti-Jeanne's only hope lies in her wits and in half-remembered bits of magical lore. An engrossing read; however, don't buy this if you object to violence. There is a good bit of that.