The number-one New York Times-bestselling author returns with another  pulse-pounding thriller featuring FBI agents Dillon Savich and Lacey  Sherlock, and introducing Speical Agents Lucy Carlyle and Cooper McKnight.     A serial killer is on the loose, and it's up to FBI agents Dillon Savich and  Lacey Sherlock to bring him down. They soon discover that the killer has  blood ties to an infamous and now long-dead monster. Savich and Sherlock are  joined by agents Lucy Carlyle and Cooper McKnight, and the chase is on.    At the same time, Agent Carlyle learns from her dying father that her  grandfather didn't simply walk away from his family twenty-two years ago: he  was, in fact, murdered by his wife, Lucy's grandmother. Determined to find  the truth, Lucy moves into her grandmother's Chevy Chase mansion. What she  finds, however, is a nightmare. Not only does she discover the truth of what  happened all those years ago, but she faces a new mystery, one that has been  passed down from mother to daughter for generations.