Obsession. The Sharon Hayes Detective Series, #3

Sharon Hayes returns to the Bronx Central, NYPD, Homicide Division intending to beg for her old job back. Her old partner, Art Banks, is now in charge of the division. She walks into his office preparing to plead her case when Art says, without looking up from his desk, "You're hired." Sharon easily slips back into her old job, but she needs a new partner. Nikki Nobles, all 6'8" of her is waiting in the squadroom.
Sharon takes an immediate liking to Nikki and finds herself blurting, "I am going to need a new parter." And that's all it takes. Sharon, or "Styx" as her friends call her, and Nikki are now partners. Their first case, the grisly murder of an aged but very well preserved prostitute, leads them to a very tangled web of serial murders and more: there is ritual involved in each murder case they uncover.
The dead prostitute turns out to have had several previous identities, each of which can be traced to murder and mayhem going back fifty years and more. They find themselves workig with the U. S. Marshalls, Marshall Drew Dryer by name, and Sharon picks up on something odd between Nikki and Drew...do they know each other? Are they working to solve the crimes or cover them up? Working with Val Smyth-Colson, the voice in her head, Styx plies her detective skills to determine what exactly is going on, and finds it.
And where would this search eventually end? Why, with her murderous and demented birth father, of course: Denny Doyle is back, and he is not alone...