Carma Hinton is one American who can claim to understand the Chinese protest movement - she grew up there during the Cultural Revolution. She tells Isabel Hilton about her six-year mission to give a voice to those caught up in the events of 1989
In the first few moments of her remarkable documentary on Tiananmen, Carma Hinton's narration says, "When individuals stand up to power, they bring the lessons that power has taught them and the harm it's done them." It's a thought that sets the interpretative framework for the next 90 minutes, a scrupulous, sometimes lyrical and deeply moving examination of the tragedy of the Beijing spring and the attitudes - on both sides - that brought the tragedy about.

Standing up to power and changing society is something of a theme for Carma Hinton, a theme matured in two generations of her family and tempered by her own personal history. "People listen to my accent and try to guess where I'm from," she says. "They never get it. The closest anyone has got is Turkey." The accent is, in fact, Chinese, but it's unguessable because in outward appearance the well-groomed Ms Hinton is a poised, middle-class American. But her English was learned, first patchily and reluctantly in Beijing, then, with dogged application, in the United States where she went to study in her late teens. It remains lightly - and strangely - accented.

Until she went to the United States, she was, as nearly as it's possible for someone who was technically a foreigner to be, a product of the People's Republic of China. That she was born in China was the result of her parents' desire for social change. Her mother's family she describes as "left, liberal, establishment". Her father, William Hinton, was an American agriculturalist who went to China on a contract with UNRRA (the now defunct United Nations Relief and Rehabilitation Administration) in 1947. There, in a village called Longbow, he witnessed the beginnings of the Chinese Communist Party's land reform.

The Communists did not establish control over the whole of China until 1949, but they experimented with their social policies in the liberated areas. Hinton was deeply impressed and his book, Fanshen, was to become one of the classics of the Chinese revolution. The Hintons stayed on beyond William Hinton's UNRRA contract, anxious to contribute to the success of the revolution. Then, in 1953, William, irritated by the predominance of the Russian "experts" who had arrived in large numbers to ensure that Stalin's ideas were respected by this fledgling Communist state, returned to the United States. His wife stayed behind, content with her teaching job in Beijing and wary of a homeland that was, by then, in the grip of McCarthyism. Young Carma stayed with her and grew up the Chinese way.

"When I was really small, I had a Chinese nanny and I spoke only Chinese. After that, I refused to speak English, so my mother had to speak to me in Chinese." She attended primary and secondary school, conscious that she was called a waiguoren (far country person) but not knowing which far country she came from. It wasn't until the Cultural Revolution, when Carma Hinton was in high school, that her identity became a problem.

"People have the impression that foreigners were directly attacked in the Cultural Revolution, but that wasn't the case, at least not in the beginning. Those who were married to Chinese - mostly women - were attacked because it was a way of getting at their Chinese husbands. But later foreigners got involved with various factions - then rival factions would kidnap them and hand them over to the police." In the early stage, in her own school, Carma observed that the Red Guards were the children of the party elite. "They analysed all the pupils on the basis of their class background. When they came to me, they didn't really know what to say." As the Cultural Revolution progressed, Carma and her friends found their own voice - their criticisms were directed at the absolutist style of the Red Guards. "We were a very close group of friends and we all had ideas for change and for educational reform, but we were against the oppressive style of politics of the Red Guards." Hinton was never physically attacked in the Cultural Revolution, but she was verbally abused and it became clear, as events unfolded, that being an American was a liability not just to her but, more importantly, to her friends. She decided to leave.

Perhaps it was that experience that informed her understanding of Tiananmen in 1989 - that and a frustration with the blanket, and yet she felt, uninformative coverage of the events that she watched with her husband and fellow filmmaker, Richard Gordon, on American television. "As I was watching it, I realised that hardly any Chinese got to finish a sentence, let alone a whole idea. The big anchormen went in and they became the heroes who discovered the story - the events, the buildings and the people were just a stage set for them. Since I knew lots of people from my childhood, I knew there were lots of different opinions on how to go about change and how to get more power for individuals, but none of that came through." The idea of making her own film came gradually. "I was reluctant. I knew it would be hugely difficult and I wasn't about to rush off there and make a film. I knew it would take years and that I would be attacked from all sides. But what finally tipped me into it was the fact that the opinions of the people who took part just weren't getting through. I wanted to widen the spectrum of voices. So often China is seen in black and white terms - in this case, the evil government and the heroic students. It wasn't the reality. I felt people should be able to understand China in the same terms that they understand themselves, not as something alien or different."

It did take years - six years, in fact. And she has been attacked from all sides. The Chinese government responded with furious protest when the film was shown in Hong Kong and New York. And the student leaders in exile accused her of being in league with the government. If she finds it amusing, it's because that is the point that the film makes. This is not a documentary of black hats and white hats: it's a meticulous retelling of a protest that was drawn towards bloody confrontation because the voices in the square - voices like Chai Ling, the student leader whose emotional interview with an American reporter features large in the documentary - were unable to back down. It was a matter not just of the compulsion of their own power: it was also that their political ideas were as absolute as the hardliners in the government they dreamed of overthrowing.

"The students all ask me, `What can we do next?' " sobs Chai Ling, days before the crackdown. "How can I tell them that what we are hoping for is bloodshed... only when the square is awash with blood will China awake." Reformers on the government side, led by Zhao Ziyang, tried desperately to defuse the confrontation, only to go down, in the face of student intransigence, to the hardliners. Chai Ling got her bloodshed, but as others died or went to jail, she herself escaped to a new life in the United States. She refused to be interviewed for the film.

"The tragedy was," says Carma Hinton, "that in 1989, the reformers were moving away from the view that social protest was the result of enemy action. They argued that it was a normal part of any society and if they had won out, the idea that protest was normal and could be dealt with would have been established. It might not have ended in tragedy."

Canna Hinton and Richard Gordon's documentary `The Gate of Heavenly Peace"' will be shown on BBC 1 tonight at 9pm