In the early 1970s, at the height of the civil rights struggle, racial riots broke out in the big cities of the United States. Ron Stallworth becomes the first Black American officer of the Colorado Springs Police Department, but his arrival is greeted with skepticism, even outright hostility, by the lower-ranking officers of the police station. Taking courage with both hands, Stallworth will try to move the lines and, perhaps, leave a trace in the story. He then set himself a mission of the most perilous: infiltrate the Ku Klux Klan to denounce abuses.
By pretending to be an extremist, Stallworth contacts the small group: he is not slow to be invited to integrate the bodyguards. He even has a special relationship with the Klan's "Great Wizard," David Duke, delighted by Ron's commitment to a White America. As the investigation progresses and becomes more complex, Flip Zimmerman, colleague of Stallworth, pretends to be Ron during meetings with members of the supremacist group and learns that a deadly operation is preparing. Together, Stallworth and Zimmerman team up to neutralize the Klan, whose real goal is to sanitize his ultra-violent speech to appeal to as many people as possible.