When Ron Stallworth, the first black detective in the history of the Colorado Springs Police Department, comes across a classified ad in the local paper asking for all those interested in joining the Ku Klux Klan to contact a P.O. box, Detective Stallworth does his job and responds with interest, using his real name while posing as a white man. He figures he'll receive a few brochures in the mail, and learn more about a growing terrorist threat in his community. A few weeks later the office phone rings, and the caller asks Ron a question he thought he'd never have to answer, 'Would you like to join our cause?' This is 1978, and the KKK is on the rise in the United States. Ron answers the caller's question that night with a yes, launching what is surely one of the most audacious, and incredible undercover investigations in history.