They are so young and so brave. Maybe you can only be that brave when you are young. Idealism and hope fuel your courage, along with the secret belief that you are in all likelihood immortal.

Dispatches: The Battle for Hong Kong followed a handful of protesters taking part in the pro-democracy demonstrations that recently took place after the region’s government proposed an extradition bill that would allow its people to be sent for trial in mainland China. The move struck a spark in the tinderbox of fears that have been growing as Hong Kong reaches the halfway point of the 50 years of special protection it was granted when the British handed the colony back to China in 1997. It remains – so far – a sanctuary; not perfect, but a relatively safe corner of a country whose Communist-turned-nationalist history has otherwise made corruption endemic and human rights abuses commonplace.

The extradition bill is a shot across the bows. The people mobilise. Many of them are secondary school students; this is a movement in which 22-year-old Agnes Chow (charged with unlawful assembly and inciting others and facing a potential five-year prison sentence) is considered a veteran. One of them, Vincent, was born in mainland China and moved to Hong Kong with his family in his teens. He grew up, he says, so tightly surveilled by the state “it was like a prison outside a prison”. If Hong Kong falls prey to the same strictures “people will find it hard to survive”. He protests most weekends. “Give me death,” he says, without melodrama, “or freedom.” Five months of protests begin.

At first, as these things tend to be, they are peaceful. Then, at one demonstration, the police deploy tear gas and are filmed – on protesters’ phones, of course – attacking people in the crowd. Twenty-year-old Momo was one of the thousands there that day and was shocked by what she witnessed. But more profound disillusionment set in when she returned home to her partner, a policeman. “I asked him: ‘What if you shot at me and injured me?’ And he didn’t seem to care.” Her mother, too, is deeply anti-activist. “She says in foul language that the protesters need to be beaten to death.” The generational abyss can be uncrossable, and the division between families gives a sense of the scale of what faces anyone wanting to challenge China.

Putting faces to this sprawling news story and making intimate the many issues it raises is where this particular film triumphs. It is not a deep dive into China’s history, sociology or politics, but a remarkably effective and emotive depiction of the hopes and fears of real people, right now.

As the protests continue, they become more intense and more dangerous. Police spokesmen couch it in terms of extreme danger, suggesting the people are moving “one step closer to terrorism”. Vincent is protesting on the night the police fire their first live round. The government bans face masks. Momo moves up to the frontline, extinguishing tear gas missiles and providing medical help to injured demonstrators. Another protester, Lomi, assembles a team in a safe house, preparing to join the disruptions planned for 1 October, China’s National Day and a celebration of 70 years of the Communist party and the emergence of the country as a global power. Lomi writes the phone numbers of lawyers and civil rights charities on her feet.

Hong Kong’s extradition bill is withdrawn, but it is a gesture made too late. A dozen pitched battles between police and protesters take place across Hong Kong and a siege develops at the Polytechnic University when activists, including Lomi, are trapped by police. She escapes, eventually to take refuge in Taiwan. It is unlikely that she will see her family again. More than 1,000 others are arrested, in effect ending the protests – at least for now.

The most striking thing here was how little violence there has actually been. For whatever reason – from mere optics, to not wanting to stress-test relations with its volatile neighbours, or to encourage Taiwan to officially declare independence – it is clear that, even allowing for Hong Kong’s special protections, China is so far pulling its punches. What may happen if and when the protest movement gathers strength and returns, and how things will play out as 2047 comes ever closer, is a terrifying prospect. Whether there is enough youth or bravery to surmount China’s might is something I wish there were no need to test.