Few people today know that Arthur Conan Doyle, the celebrated author of the Sherlock Holmes detective stories, was also a renowned public figure and advocate for the unjustly convicted. Conan Doyle's intervention helped mitigate the sentence of his friend accused of treason, restore justice in the high-profile case of an Englishman of Indian descent who had fallen victim to xenophobia, and finally free Oscar Slater, convicted of the murder of a wealthy woman. Sentenced to death, which was later commuted to hard labor for life, Slater spent more than 18 years in prison, forgotten by almost everyone. Almost everyone, but not Arthur Conan Doyle. The writer managed to free Slater through his own investigation, using his keen observation and clear logic—the very things that brought worldwide fame to the hero of his stories. New York Times journalist Margalit Fox's book tells the story of a man sentenced to death whose innocence was proven without modern forensic methods, and of a unique investigative method described in Sherlock Holmes stories that was then applied to a real crime.