This article is supported by Blackkklansman, the new film from Spike Lee out in cinemas on August 16. In this piece, we look at the true story it was based on.

The year was 1979, the same year the Ku Klux Klan had just killed five anti-KKK protesters in North Carolina, when Ron Stallworth walked into work one fateful morning at the Colorado Springs Police Department.

As an undercover police officer in the intelligence unit, Stallworth’s job was to track any group passing through town deemed to be subversive. When he sat down at his desk to read the local newspaper, an advert in the classifieds asking anyone curious about the KKK to send word to a PO Box caught his interest.

Stallworth certainly was curious.

The Ku Klux Klan is one of those organisations which have ebbed and flowed with the times. The KKK began as America’s first domestic terrorist organisation after the American Civil War. When it fell out of fashion, the group receded until the Depression when its membership exploded to an estimated two-to-ten million people.

What marked the second era of the Klan fizzled away until the civil rights era of the fifties and sixties. So began the third era of the Klan when a constellation of separate groups took up the label and organised a campaign of intimidation, murder, rape, and arson of black-owned businesses and their supporters.

“There are many separate organisations that claim to be Klan groups and broadly share the Klan ideology that has developed over a century and a half. But the Klan is not just one group as it was in prior eras,” says Heidi Beirich, director of the Southern Poverty Law Centre’s Intelligence Project.

Today the Southern Poverty Law Centre tracks 72 distinct groups who still use the name. As much as things change, they also stay the same.

Back in 1979, Stallworth wrote a letter to the named address and sent it off, but in a moment of absent mindedness, he signed it with his real name. A few weeks went by and he had almost forgotten about it when a phone call came through to the secure phone line used by the undercover unit to conduct investigations.

The voice at the other end of the line asked for Ron Stallworth and introduced itself as Ken O’Dell, the local organiser for the KKK, who explained that they were on a recruitment drive, and asked whether Stallworth wanted to join up.

What O’Dell couldn’t have known however was that Stallworth was black—not that it would’ve been hard in a small town like Colorado Springs to check that information.

After a moment’s hesitation, Stallworth decided to lean in. Sure, he said, he’d love to join the Klan. Those words kicked off a seven-month undercover operation. While Stallworth worked the phones, a white, Jewish colleague from the narcotics division handled face-to-face meetings when they came up.

In all that time, none of those being investigated caught onto the hustle and not a single cross burned in their city. When it was all over, Stallworth had identified the local membership, including personnel stationed at a local military base.

“They were all assholes,” Stallworth told VICE about his operation. “There was no sympathy whatsoever. My only regret was that I couldn't reveal who I was and what I was doing to thoroughly embarrass them and show them what idiots they were.”

Stallworth may have never had a chance, but Spike Lee would when he took Stallworth’s story and turned it into film. In other hands, Blackkklansman could have ended up little more than a buddy-cop spoof with a fairly obvious gag, but with a pitch perfect soundtrack and a few artistic liberties, it is instead a gripping and politically relevant film.

It is hard to miss the message. The film closes with footage from Charlottesville in August 2017 when radical ultra-nationalist groups descended on the small town of 48,000. By the end, Heather Heyr, 32, would lose her life after being run down by James Alex Fields, Jr a neo-Nazi who drove his car into counter protesters, injuring 19.

In the aftermath, Justin Moore, a “grand dragon” of the North Carolina-based Loyal White Knights of the Ku Klux Klan told a reporter he was “glad” Heyer was killed.

“I’m sorta glad that them people got hit, and I’m glad that girl died,” Moore said. “To me, they were a bunch of communists out there protesting against somebody’s freedom of speech, so it doesn’t bother me that they got hurt at all.”

After a ten-minute standing ovation during its premiere at the Cannes Film Festival, Spike Lee stood to give a ten minute speech where he reminded his audience that the leader of the United States, the country that once went to war with Nazi Germany, could not find the words to denounce neo-Nazi’s and white supremacists.

“We have a guy in the White House—I’m not gonna say his fucking name—who defined that moment not just for Americans but the world, and that motherfucker was given the chance to say we are about love, not hate," Lee said.

"And that motherfucker did not denounce the motherfucking Klan, the alt-right, and those Nazi motherfuckers. It was a defining moment, and he could have said to the world, not just the United States, that we were better than that."

Trump’s silence would have been music to David Duke’s ears.

Today Duke is the most recognisable figure associated with the KKK and who in 1989 made a successful run for political office three decades before Trump.

Trading the hood for suited respectability and bona fide legitimacy, Duke ran in the Louisiana Republican primary, placing first in the initial vote and narrowly winning a second run-off against with a 50.7 percent majority.

After being turfed out of office in 1992, Duke would never again find the same success, but that didn’t stop him trying every couple of years, including another failed run earlier this year. While Duke may have been emboldened by the election of Trump, Professor Charles S Bullock, a political scientist with the University of Georgia, says he was hardly surprised that he crashed and burned.

“Duke and Trump both capitalize on voters’ fear of change – economic, racial, cultural,” says Bullock. “Duke’s appeals are more racially explicit and his background as a Holocaust denier and admirer of Adolph Hitler now place him beyond the pale for many who share some of his grievances.”

While Donald Trump, whose daughter, son in law and grandchildren are Jewish, may not have adopted the exact rhetoric of the KKK, Beirich says his Presidency has allowed other white nationalist ideas to be debated as if they were respectable.

“We should never forget that the idea of building a wall came from the white supremacist movement,” Beirich says.