In scenes from Greece relayed by the world’s media in recent years, the dominant emotion has been anger. Think of the thousands who besieged parliament after it yielded to demands from the “troika” – the European Commission, the International Monetary Fund and the European Central Bank – for harsh austerity measures in return for a bailout of the country’s ailing economy. Or the volleys of tear gas fired in central Athens by riot police whose gear looked more suitable for a war zone than a European capital city. Or the notorious rallies organised by Golden Dawn, the far-right party that won 18 seats in 2012’s legislative elections.

But Love in the Time of Crisis, a new documentary that asks how the economic disaster has affected intimate relationships, suggests something else has been emerging from beneath the surface in Greek society: a new sense of solidarity. “The plateias – the squares – changed everything,” says Anastasia Giamali, a young journalist interviewed in the film, recalling the mass protests that erupted in town squares across Greece in 2011. “It’s an unbelievable feeling to trust someone that much with your life . . . you’re not friends, you’re not siblings – you’re comrades.”

Austerity has been bitter for most Greeks; each winter now brings a rise in deaths from fire and respiratory diseases because people have been heating their homes by burning wood rather than more expensive oil. At the same time solidarity networks have flourished: volunteers from all sorts of political backgrounds provide free medical care to people without insurance, or run markets that put farmers directly in touch with consumers so that impoverished Greeks can buy cheap, healthy food. Such initiatives are meant only as stopgaps, but they point to something important: the idea that people can take control and build an alternative to policies imposed from above.

Syriza, the left-wing party that stands on the brink of power, has sought to position itself as the political voice of this wider social movement. After the collapse in December of the current government (the ruling New Democracy party failed to get enough MPs to support its candidate for president) snap elections were called for 25 January, and Syriza is ahead in the polls. Launching Syriza’s campaign on 3 January, the party’s 40-year-old leader, Alexis Tsipras, pledged to remove taxes that are hurting the poor and to take on the country’s oligarchs.

An election victory for Syriza would send shock waves far beyond Greece. By challenging austerity policies, the party threatens to undermine the consensus that has dominated European politics since the financial crash of 2008. Already, German officials have reiterated threats that Greece could be forced to leave the eurozone if its people elect a Syriza government. In a previous era, what the party is proposing – renegotiating Greece’s debts down to half their present level – might have been regarded as unremarkable Keynesian economics. But a Syriza victory now would be seen as an encouragement to popular anti-austerity movements elsewhere in Europe, including Spain, which also holds elections this year and where the far-left Podemos, founded only a year ago, has become a serious challenger.

Syriza’s victory is not guaranteed. In 2012, it polled well but was beaten by the right-wing New Democracy, which has presented itself as a moderate alternative to the “extremes” of far left and far right. Greece is still deeply divided by the legacy of civil war and dictatorship, and Syriza will face a concerted media campaign to keep it out.

What’s more, a Syriza victory would present its own problems. When I visited Greece in December, several party activists were gloomy about what they saw as their leadership’s drift to the centre. Tsipras has toured foreign financial capitals to reassure the markets that he is someone they can do business with. The grass-roots energy of 2011 has dissipated, with open public meetings giving way to cliques centred around influential figures. And there are difficult questions the party’s leaders would no longer be able to avoid. If what they want isn’t achievable within the euro, would Greece leave?

I wondered how the young journalist Anastasia Giamali felt now, more than three years on from the town square protests. She works for the Syriza newspaper Avgi, and told me that the party has a big responsibility to assist victims of austerity – and would fail if it did not. “Syriza’s plan is to act on their behalf, but it will solve nothing if the people are not beside them. Syriza is not a messiah; it needs the active participation of the people.”

Love in the Time of Crisis is available to watch at https://vimeo.com/ondemand/loveinthetimeofcrisis