On October 1, 1991, Fran Gladden-Smith disappeared without a trace from her home in Princeton, New Jersey, and suspicion immediately turned to her new husband, John David Smith III. In a highly unusual move, the police allowed her family to be involved in the investigation -- as long as they didn't interfere with law enforcement. Over the next several years, Fran's sister Sherrie Gladden-Davis played a deadly game of cat-and-mouse, tracking Smith and his activities across the United States. She could go where police couldn't -- and she dedicated herself to helping authorities get the evidence they needed to unravel the mystery of her sister's disappearance. "My Sister Is Missing" is Sherrie Gladden-Davis's harrowing account of the search for her sister's killer, and the inspiring story of her extraordinary path to justice.