All her life Ellie Enderlin had been known as Lila’s sister. Until one day, without warning, the shape of their family changed forever. Twenty years ago, Lila, a top math student at Stanford, was murdered in a crime that was never solved. In the aftermath of her sister’s death, Ellie entrusted her most intimate feelings to a man who turned the story into a bestselling true crime book—a book that both devastated her family and identified one of Lila’s professors as the killer.