An urgent public-health situation is unfolding among Indigenous communities in the Brazilian state of Roraima. Health workers trying to tackle the problem, which includes a deadly malaria outbreak, must deal with the complex mixture of biological and political factors that have led to the current situation and that could act as obstacles to potential solutions. In this documentary, Nature explores how mining, migration and changing government policies influence the spread of malaria, and discovers the methods being used to manage the disease.