Set in the post-Civil War period, the film chronicles the rise of the KKK in the American South in 1865 and the man who led the U.S. Army's elite K Troop that stomped out the group in 1871.

The white supremacist organization later rose again in 1915 and flourished nationwide in the early and mid-1920s, evolving from its anti-black philosophy to a broader opposition to Catholics and Jews. The third incarnation of the KKK emerged in the Civil Rights era of the 1950s and continues to this day, with a new emphasis on anti-immigration.