Marie Belloc Lowndes was one of the first novelists to base her work on historical criminal cases, at times utilizing actual courtroom testimony. This innovation, however, presented her with a dilemma: If the reader knows the outcome of the problem, where is the suspense? Lowndes’s solution was to focus attention not on the crime but on the underlying motives and, above all, on the reactions of those affected by its consequences. Most of her characters, whether murderers, accomplices, or bystanders, are ordinary people who, to their horror, become gradually enmeshed in circumstances beyond their control. Lowndes, unique in her day, was particularly adept at portraying the psychology of women who not only shielded criminals but also could be cold-blooded killers. It is to one extraordinary, even mythical, figure in criminal lore, however, that Lowndes owes her place of honor in the mystery hall of fame. In The Lodger (1913), she was the first to seize on the rich material latent in the Jack the Ripper murders. She also was the first to participate in the game of guessing the Ripper’s identity. Her assumption that the hierarchy of the Metropolitan Police knew and covered up the identity of the murderer has formed the basis of many subsequent theories concerning the notorious serial killer.