On the outskirts of Beijing, two teenage girls from a migrant family struggle to earn the money to pay for their brother's schooling with little help from their troubled and eccentric parents.

Growing up in a rickety hut on a garbage-filled lot, Xia, Ling, and Gang recognize that a good education is their only possible ticket to a better life. Their older sister, who left school to begin working, has disappeared, likely kidnapped and sold into prostitution.

As migrants, they are prevented by China's hukou (residence permit) system from attending a free public school, and when the school that had provided them with scholarships closes, they are forced to look for new options. With very little money to their name, they place all their hopes in Gang, the older brother.

Their complicated home life doesn't make things any easier. Their alcoholic father and their mother are frequently at one another's throats, and do not seem to understand the gravity of their children's situation.

Director Ji Dan, one of China's preeminent female filmmakers, first met Xia, Ling, and Gang in 2004, while making a film about education in China, This intimate, patient portrait grew out of their close relationship over many years.

WHEN THE BOUGH BREAKS at once explores the particular dynamics of one family and exposes the widespread difficulties faced by migrants living at the margins of Chinese society.