In the 1980s, David Duke, a former grand wizard of the Ku Klux Klan and a statehouse legislator in Louisiana ran for the U.S. Senate and for governor. He didn’t win, but the fact that he was a major contender was itself a reckoning for the state. For the fourth installment of this Slate stalwart, host and Louisiana native Josh Levin delves into the story of how a smooth-talking man put a slick sheen on white supremacy — and convince the electorate to follow.