Kim Harrison's Cincinnati is located in a United States in which witches, vampires, werefolk, and other creatures formerly thought of as inhabiting fable and fiction live side-by-side with humans. Or they have for the last forty years, since "The Turn," when humanity decimated a large percentage of its population with bioengineered diseases...diseases which had no effect on the non-humans they had no idea had always existed alongside themselves.
Rachel Morgan is a witch who works as a runner, bringing down lawbreaking members of the supernatural, or Interlander, community. She's got a price on her head, her roommate and business partner is a non-practicing vampire, and a pixie family lives in her garden.
Kim Harrison has posited an intriguing world, and worked out many of its details in an original and satisfying fashion. Her writing, however--at least in this, the first installment of the series--is awkward and rather hackneyed.
Good for fans of Jim Butcher or Rachel Caine jonesing for a fix between installments.