Since the rise of magic, beings like werewolves, magicians and vampires have come to the fore. It is those beings that we see do battle when the "magic field" is on. In this book, Kate Morgan looks into who killed her guardian (who was a chief magician, for want of a better description).
The story reminds me of Laurel K. Hamilton's Anita Blake series, but with the key difference that it focuses on story, rather than who the central characters fancy. Because of that I'd say the series has potential. It should attract the Hamilton readers who actually believe in storylines.
This having been said, the book is far from perfect. It's good, but it can be a bit busy in places. It's a short book, but Ilona Andrews (the author) seems to have attempted to pack as much story as possible into the book. You want to say "enough already" on occasions, but that having been said, the series is one worth watching.
Before I sign off, I would like to say one thing. I wish someone could show me a good "magic/vampires" series which doesn't end up becoming more about who the lead character fancies. I liked the original premise of both Laurel Hamilton's and Kin Harrisn's books but recently they've become more about who the lead character fancies, rather than story. Maybe that's because they're really "chick lit" and I just misunderstood the point of the story, but I still feel like there should be room for a good detective story in that setting.