The world of the books is almost ours. Magic has recently returned after a long dry spell, so all sorts of dangerous creatures and effects are popping up. The lupi are, we learn eventually, created beings meant to serve as soldiers in a magical war (which is why they are all male; they can breed with humans, but only their male offspring are lupi). Rule has a lot of political power among the lupi, and serves as a mediator between lupi and humans; Lily works for a special branch of the FBI that deals with magical beings and happenings.
Wilks keeps the series interesting by gradually making the world more and more complicated, and adding in new characters here and there, often in small roles that grow as the series progresses. The end of this book reveals where the series is going next; I won't spoil it here, but I tell you because I think this is not the book to start with. I'd start at the beginning of the series, Tempting Danger.