No One You Know

Twenty years ago, Ellie Enderlin's sister, Lila, a brilliant mathematician, 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. Decades later, Ellie receives a piece of evidence never found with her sister's body: a notebook of Lila's filled with mathematical formulas. It will lead her to a hundred-year-old mathematical puzzle, to a lover no one knew Lila had, to the motives and fate of the man who profited from their family's anguish…and to the deepest secrets even sisters keep from each other.