In Blackkklansman, visionary filmmaker Spike Lee has created a film that is hilarious, terrifying, tense and all too true. Set in the 1970s, the film details how Ron Stallworth (played by John David Washington) – the first black detective on the Colorado Springs Police Department – bravely sets out on a dangerous mission: infiltrate and expose the Ku Klux Klan.

Wait, what? A Black man went undercover in the KKK and posed as a racist extremist? Spike Lee is known for being outrageous and satirical, but that premise is just ridiculous, isn’t it?

It’s all too real.

In October 1978, Stallworth successfully infiltrated the local chapter of the Ku Klux Klan in Colorado Springs. The movie is based on Stallworth's 2014 book Black Klansman, which details his experience.

As shown in the movie, Stallworth initiated contact by responding to a classified ad in the local newspaper, and received a phone call from the Klan soon after. Stallworth used these phone conversations to ingratiate himself with Klan members, to build trust and gather intel – though of course, when it came time to meet the Klan members face-to-face, he couldn’t just show up in person.

But neither did he want to remove himself from the case and lose all the valuable intel he had already collected. So Stallworth enlisted the help of a white undercover narcotics officer (named Zimmerman and played by Adam Driver in the film, though this officer’s real name is not on record), who posed as Stallworth for all in-person meetings with the Klan.

Hollywood, pay attention: these are literally the only circumstances in which it’s acceptable for a white person to play a black person.

Together, Stallworth and ‘Zimmerman’ teamed up to take down the organisation, whose aim was to figure out to sanitise its violent rhetoric so that it would appeal to the mainstream. When you think of how quickly we have adopted racists' self-branding labels like "alt-right", which have allowed them to flourish, instead of referring to them as white supremacists or neo-Nazis, it's easy to understand why branding was the important issue at the time.

The real investigation went on for approximately nine months, and together Stallworth and Zimmerman were so effective in their mission to infiltrate the Klan that Stallworth was actually nominated as a leader for his local chapter of the Klan – a role he did not take on, as the police chief was understandably concerned of how public perception would play out once the investigation was over. Stallworth and Zimmerman co-ordinated and shared their intel so effectively that no-one suspected that the on-phone Stallworth and in-person Stallworth were different people - and the one time Stallworth's voice was questioned, he said he had a sinus infection.
During this time, Stallworth had several phone conversations with David Duke, the self-proclaimed “Grand Wizard” of the KKK.

In an interview with NPR, the real Stallworth explained that, “The Colorado Springs chapter was under the auspices of David Duke's Invisible Empire. I had mailed in my application, and after I didn't receive any response in two or three weeks, I decided to go directly to the horse's mouth, so to speak. I called David Duke directly down in New Orleans. And the day I called, lo and behold, he answered the phone."

Duke told Stallworth that there was a delay in processing applications and that he would personally see that Stallworth's application was processed and sent back to him. It wasn't long before Stallworth received his Certificate of Citizenship in the KKK's Invisible Empire, which was signed by David Duke. Stallworth says that he continued to talk to Klan leader David Duke "off and on during the course of the investigation."

In the film, Duke is played with brilliantly evil banality by Topher Grace, and there’s a hilarious satisfaction in watching Duke be deceived by a black man. One particularly memorable moment from their onscreen conversations was based on a real interaction. During one of their phone conversations, Stallworth asked David Duke, "Aren't you afraid of an undercover police officer infiltrating your organisation or maybe a black man calling you up and pretending to be white?" Using the N word, Duke confidently told Stallworth that he could always tell when he was talking to a black person.

Spoiler: David Duke was incorrect about this, like so many other things.

The overall investigation lasted nine months, during which Stallworth and his partner gathered intel on KKK members and operations, thwarted several cross burnings and rallies, and gained the trust of KKK leaders, including KKK Grand Wizard David Duke. They also uncovered high-profile Klan members, including military officers and members of the North American Aerospace Defense Command. Stallworth and his partner also heard about plans to bomb the two gay bars that were in Colorado Springs at the time, but no terrorist action occurred during Stallworth’s investigation.

Though, disappointingly, no arrests were made during the investigation, Stallworth considered the intel gathered and the thwarted cross-burnings a success, writing in his book that “as a result of our combined effort, no parent of a black or other minority child had to explain why an 18-foot cross was seen burning. No child in the city limits had to experience first-hand the fear brought on by this act of terror.”

Spike Lee’s film draws some obvious parallels to the racism that is still prevalent in America today, including the rise of hate crimes, Neo-Nazis and the devastating events in Charlottesville, Virginia last year, when a ‘Unite The Right’ rally turned into a violent brawl, as white supremacists attacked counter-protesters, injuring over 34 people in total and killing Heather Heyer, who was struck with a speeding car.

The real Stallworth thinks these parallels are vital and necessary, telling journalists that America’s problem with racism "hasn't changed. To me, race is the single most divisive factor affecting American society. It's an issue that we are afraid of, that we shy away from; and quite frankly, it amuses me that we are so sensitive to the issue."

Blackkklansman is in cinemas from August 24.