The remarkable story of Arthur Conan Doyle’s defense of convicted murderer Oscar Slater weaves together so many topics that need contextualizing: the state of early 20th-century forensic science; British anti-semitism; ideas about race and criminality; and the waning of Victorian elites in the Edwardian period. As a result Margalit Fox’s book is a bit slow in the first third, with so much backstory needed. But once the plot picks up, ‘Conan Doyle for the Defense’ is an extraordinary tale. None of these historical actors are unmitigated heroes—the police especially—but even the detective writer shows himself a bit of a crank toward the end. Nevertheless the story of Slater’s unjust conviction and its eventual overturning is a compelling story of persistence and a belief in justice. Fox has mined an extraordinary set of sources, including almost 20 years of letters from Slater to his family back in Germany through two World Wars. Ultimately she even ventures a guess as to who *really* murdered Miss Marion Gilchrist. Well worth a read.