On March 29, 1975, young sisters Katherine and Sheila Lyon vanished from a mall in suburban Washington, D.C. After police found nothing, the investigation was shelved, until 2013, when a cold case detective found a suspect who was now serving time in Delaware. As a cub reporter for a Baltimore newspaper, Mark Bowden covered the frantic first weeks of the story, and here he returns to write its ending. Spending months investigating a sprawling, sinister Appalachian clan, five skilled detectives raced to solve the mystery, but this case would prove hard to close.