Showing Master of the Moon by Angela Knight

Unknown to the citizens of her small town, policewoman Diana London is a shape-shifting werewolf on the track of a killer vampiress. Through erotic dreams, she is drawn to Llyr, king of the faeries. But despite sparks, Llyr is a complication in her life. Until the vampiress at large finds an ally, Diana and Llyr have no one to turn to but each other.