To investigate the reasons behind the Bewick swan population's shocking decline, female environmentalist SACHA DENCH takes to the skies in a paramotor to follow the flock on its migratory journey, over 7,000 kilometers, and 11 countries, from Russia to England, across wetlands, tundra and industrial landscapes, where she encounters local people just as passionate about saving and protecting the swans. Narrated by Sophie Okonedo.