In 2015, an iron ore tailings dam burst near Mariana, in the state of Minas Gerais, Brazil. The waste was dumped into the Doce River and travelled 650 km, before crossing the state of Espírito Santo, and reaching the Atlantic Ocean. This was the greatest socio-environmental crisis my country has ever known. Retracing the same path, this film encounters those whose lives and land were transformed as they fight to make their voices heard.