In 1978, Ron Stallworth was working as a detective in the Colorado Springs Police Department when he came across a classified ad to find out more about the Ku Klux Klan — and answered it. Two weeks later, he got a call on the police department's undercover operations line. It was the local KKK organizer. He asked why Stallworth wanted to join the Klan. "I said I wanted to join because I was a pure, Aryan, white man who was tired of the abuse of the white race by blacks and other minorities," Stallworth recalls. But Stallworth — a...