Every spring, China's cities are plunged into chaos as an astonishing 130 million migrant workers journey to their home villages for the New Year's holiday. This mass exodus is the largest human migration on the planet, an epic spectacle that reveals a country tragically caught between its rural past and industrial future. Working over several years in classic verite, Chinese-Canadian filmmaker Lixin Fan travels with one couple who have embarked on this annual trek for almost two decades.