Just before Christmas, the body of a sixteen-year-old girl is found along the train tracks on the outskirts of a small town. As Detective Lucy Black investigates the teenager's tragic last hours in search of clues to her death, she realizes that some of the victim's friends may have been her most dangerous enemies--and that whoever killed her is ready to kill again. Haunted by the memory of a case gone wrong, and taunted by a killer on the loose, Lucy finds herself pitted against a lethal opponent hiding in plain sight.