Made to be Broken - Kelley Armstrong

To the outside world Nadia Stafford is a smart, good-looking, law-abiding citizen. Well, two out of three's not bad...An ex-cop with a legal code all her own, Nadia has a secret life as a world-class assassin. She works only for one New York crime family, who pay her handsomely to bump off traitors. But when a troubled teenager and her baby vanish in the woods near her home, Nadia's old detective instincts - and the memory of a past loss - compel her to investigate. With her enigmatic mentor Jack to support her, Nadia unearths sinister clues that point to an increasingly dark and deadly mystery. As her obsession over the case deepens, Nadia realizes that the only way she can right the wrongs of the present is to face her own painful ghosts - or die trying. And so she sets off on the trail of a young woman no one else cares about - and a killer who is bound to strike again...