Margaret Garner was the runaway slave who, when confronted with capture just outside of Cincinnati, slit the throat of her toddler daughter rather than have her face a life in slavery. Her story has inspired Toni Morrison’s Beloved, a film based on the novel starring Oprah Winfrey, and an opera. Yet, her life has defied solid historical treatment. In Driven toward Madness, Nikki M. Taylor brilliantly captures her circumstances and her transformation from a murdering mother to an icon of...