Heralded as a landmark achievement upon publication, Ida: A Sword Among Lions is a sweeping narrative about a country and a crusader embroiled in the struggle against lynching--a practice that imperiled not only the lives of black men and women, but also a nation based on law and riven by race.

At the center of the national drama is Ida B. Wells (1862-1931). Born to slaves in Mississippi, Wells began her activist career by refusing to leave a first-class ladies' car on a Memphis railway and rose to lead the nation's first campaign against lynching. For Wells, the key to the...