A quiet coastal village in India’s Gulf of Kutch is the site of an ancient fishing community’s heroic battle against some of the largest financial institutions in the world. Once a vibrant place of rich biodiversity, the area underwent a dramatic transformation after Tata, India’s largest conglomerate, installed a coal-fired power plant despite local opposition. Soon after, fish began to disappear from the region, wreaking havoc on the ecosystem as well as the villagers’ livelihoods. Shot over 10 years, Sheena Sumaria’s compelling documentary witnesses an astonishing fight for justice, against all odds.

While operated by Tata, the plant was partially funded by the International Finance Corporation (IFC), the World Bank’s private sector arm. As a result, the fishers, with the help of environmental lawyers in Washington DC, brought a lawsuit against the IFC. Their claims, however, were dismissed by US courts, where judges deemed that the IFC, and by extension the World Bank, could not be held accountable for their investments. In this sense, such institutions are above the law. Still, hope remained, as the team continued to bring the case to the US supreme court.

In strictly narrative terms, as it zigzags between the US and India, the film could have shed more light on the relationship between the fishermen and the legal team; they seem to exist in separate, parallel worlds, even when their goals are one and the same. Compared with the rather sterile US sections, the day-to-day life of the villagers is much more dynamically shot. And one of the most stirring themes is how the community’s struggles are expressed in songs. From time to time, the village’s elders would sound a melody that immortalises their turmoil. Even if officials choose to look the other way, their plight will live on through these memorable oral traditions.

• The Fisherman and the Banker is at Bertha DocHouse, London, from 28 September.