Ron Stallworth, the first black detective in the Colorado Springs Police Department, was scanning a local newspaper in October 1978 when he spotted a classified ad placed by the Ku Klux Klan:

“For more information,” the ad said, “contact P.O. Box 4771, Security, Colorado.”

Stallworth responded to the ad with a short note:

“I told them I was a white man who hated n——, spics, Chinks, Jews, Japs and anybody who wasn’t pure Aryan white like I was,” Stallworth recalled during a recent phone interview. “I told them I wanted to do something to stop the abuse of the white race.”

But Stallworth made a mistake. “I signed my real name, instead of my undercover name,” he said, “and mailed it off, thinking I would get a pamphlet, brochure or something.”

Two weeks later, the phone rang at Stallworth’s desk.

It was the organizer for the local Klan chapter in Colorado Springs.