Oliver Stone has made a career of mapping out pivotal moments in American culture to bring us politically charged films such as Platoon, Born on the Fourth of July, Nixon, The People vs. Larry Flynt and JFK. But when the 70-year-old Oscar-winning director became interested in making a movie about Edward Snowden – the man responsible for what has been described as the most far-reaching security breach in US intelligence history – he realised the stakes were much higher.
"Ed may go down in history as one of those guys who actually made a difference to his time," Stone says solemnly, as we sit in a hotel in San Diego, California, overlooking costumed fans at an annual Comic Con event. As he glances out the window, he can't help wondering if his movie will garner attention here from this community of geeks and outsiders.
"This is a huge issue, what this film raises," he declares in his booming voice, "and this is the beginning of a new generation that won't even know what they are losing. Ironically, a lot of them are here today, in the streets of San Diego, and I think many of them still take things for granted about their privacy."
The film begins in 2013, when Edward Snowden, played by Joseph Gordon-Levitt, has quietly left his job as a contractor at the US National Security Agency and flown to Hong Kong to meet with two journalists from The Guardian newspaper and an award-winning filmmaker. The virtuoso programmer was a self-declared patriot and former soldier who had become angry and disillusioned after discovering a mountain of data assembled by tracking all kinds of digital communications from ordinary citizens.
During the meeting in Hong Kong, he handed over a vast tranche of top-secret files that revealed US government cyber-surveillance programs of epic proportions, instantly making him one of America's most wanted men and an icon of popular culture at the same time.
Oliver Stone, no stranger to controversy, initially flew to Russia to meet with Snowden's lawyer, Anatoly Kucherena, about making a fiction movie loosely inspired by Snowden's own story. But once he was introduced to the youthful-looking reluctant hero – trapped outside the US after his passport was revoked and granted temporary asylum in Russia – his focus shifted.
"It was only after we had met three times, each time over a different trip, that we mutually decided to go ahead with the realistic version of his life story," Stone says.
"There was all this controversy, with some people saying he should be hanged and others wanting to give him a Nobel Prize, so we were looking for a story that reflected the reality of his present situation and decided the core of the 10-year journey in the film could be found in the tense six days inside that Hong Kong hotel room where they were all waiting to get the material out and had no idea who could come bursting into the room at any moment to arrest them all."
After a screening of the film at Comic Con, attended by Stone and his actors, a bespectacled Snowden made a surprise appearance via satellite and confessed he was still conflicted about the decision to collaborate on a movie. "I don't think anybody looks forward to having a movie made about themselves, particularly someone who is a privacy advocate," the 33-year-old exile said.
Despite those hesitations, Snowden agreed to make a compelling cameo appearance in the film. He said: "It made me nervous but I think there's a kind of magic to it and I think it works."
Gordon-Levitt recently won acclaim portraying real-life French high-wire artist Philippe Petit in the drama The Walk, but the 35-year-old actor known for films such as Inception and The Dark Knight Rises says this challenge was nothing like his previous roles.
"I've never been on the phone with a producer before a film to say, 'Can you guarantee me I'm going to be 100 per cent safe?' " Gordon-Levitt says. "But I went to Russia and it turned out I was quite safe and I got to spend about four hours with Ed and his girlfriend Lindsay Mills [who recently relocated to Russia to be with Snowden] and really get a sense of who he was besides all of his politics, so that was important to me."
Stone says Snowden's girlfriend, a yoga and pole-dancing instructor, was the key to understanding the mystery man at the centre of the controversy in human terms, and he was excited when he received a letter from Shailene Woodley offering herself for the role. Already a star with her own franchise (Divergent), Woodley is also fiercely political, having spent a large part of the year on the campaign trail with presidential candidate Bernie Sanders, and has an earnest doe-eyed look about her when asked about her motivation.
"It wasn't just wanting a job, although I did ask him for an audition," the 24-year-old says, "but I wrote to thank him for having the courage to make a film like this because as a young woman knowing about privacy issues – outside the fact my privacy is already limited by the Hollywood side – I felt like growing up we always heard about 'big brother' watching and when Ed released what he released, it verified and validated all of those suspicions and fears and sent a chill up my spine."
Few filmmakers have been as controversial as Stone, whose mantra seems to be "to hell with the consequences". Even at Comic Con, he couldn't help ruffle feathers by publicly describing the app sensation Pokemon Go as "totalitarian" and suggesting "they are data mining every single person in this room for information, so it's a whole new level of invasion".
Stone grew up in a deeply conservative family in New York with a father who served as a colonel on General Dwight D. Eisenhower's staff in Paris, post-World War II. After attending Yale University with classmates such as George W. Bush and John Kerry, the current US Secretary of State, he dropped out to teach English in Saigon, Vietnam, and later enlisted in the army. After two tours of duty in Vietnam, Stone returned home in 1968 with two Purple Heart medals, a Bronze Star for Valor and a transformed outlook on the world as an anti-establishment rebel full of an almost radicalised hatred of the establishment that still bubbles to the surface when he's talking politics.
"It's very much a 1984 world," Stone says, in a nod to George Orwell's tyrannical tale. "We are all being told how to think and being manipulated and while I think it's important the Democratic party gets to appoint the next Supreme Court justice, on the other hand you have Mrs Clinton, who is one of the greatest warmongers of our generation, and that makes me very concerned about her attitude and aggression towards foreign countries."
In the hands of an expert filmmaker like Stone, the story of Edward Snowden has depth and emotion. Not surprisingly, the director has a unique relationship with many of his movie alter-egos after his own experiences in life.
"My growth of consciousness has sometimes cost me dearly but this is my journey and it's important stuff," he says. "The stories I told about the Vietnam War or JFK or Nixon, those were revelations to me at the time and this is what I am going through now with the Snowden revelations.
"In the end, I can really only go by my own sense of the truth. If it's the truth, I want to put it in my movies."
Snowden is out in cinemas on September 22.
WHISTLEBLOWER MOVIES: A ROLL CALL
Edward Snowden isn't the first person whose conscience made him risk everything. Here are some other memorable films about whistleblowers.
On the waterfront (1954)
The classic film about a worker (Marlon Brando) who agrees to risk everything to give evidence about union corruption on the docks of Hoboken, New Jersey, after he unwittingly helps facilitate a union-authorised murder.
All the President's Men (1976)
Robert Redford and Dustin Hoffman star as Washington Post reporters Bob Woodward and Carl Bernstein, who expose corruption in the Richard Nixon administration after receiving tips from a man who identifies himself only as Deep Throat.
The film, based on a true story, stars Meryl Streep as Karen Silkwood, an employee at a plutonium plant and a union activist. After being contaminated by radiation, she exposes the plant's cover-up before dying under mysterious circumstances.
The Insider (1999)
Russell Crowe plays a former research biologist for a cigarette company who agrees to do a 60 Minutes interview to reveal that tobacco companies were not only aware that cigarettes were addictive and harmful, but worked to increase their addictiveness.
Erin Brockovich (2000)
Julia Roberts won an Oscar portraying the working-class single mother who, as a law clerk, stumbled upon evidence that a big gas and electric company was knowingly poisoning people through contaminated water and helped to organise a major class-action lawsuit against them.
The Most Dangerous Man In America: Daniel Ellsberg and the Pentagon Papers (2009)
A documentary about Daniel Ellsberg, a US military analyst working for the RAND Corporation in 1971 when he accessed and leaked thousands of top-secret documents that became known as the Pentagon Papers, infuriating the Nixon administration.
We Steal Secrets: The Story of WikiLeaks/The Fifth Estate (2013)
The documentary looks at the rise to prominence of WikiLeaks founder Julian Assange and his war on secrecy while the movie, The Fifth Estate, is a fictional version of the story starring Benedict Cumberbatch as the famed hacker now living in exile.