Yang Bailao, a tenant farmer, lives with his daughter Xi'er. The despotic landlord, Huang Shiren, attempts to forcibly take Xi'er for himself. On the eve of the Chinese Spring Festival, Huang forces Yang to sell his daughter as repayment of the debt Yang owes him.

Adapted from a novel of the same title, this film depicts a young woman’s transformation from housewife to loyal Communist. This process is presented as “natural” – possessed of inherent logic rather than merely “incidental”. Hence, the film is really about Communist revolution that won over the hearts and minds of Chinese youth.

In 1948, after the Northeast was liberated, enemy sabotage began. The Public Security Bureau learned that spy Li Tianmin had infiltrated the city. Bureau chief and Captain Zhang quickly deployed personnel to capture him. Li Tianmin evaded key questions during interrogation. Clues were found on a milk bottle cap delivered by a boy, who passed it to another spy, Zhou Shaomei. Under surveillance, Zhou Shaomei, fearing Li Tianmin’s capture, killed the boy to erase evidence. Intelligence personnel mobilised the masses, pressuring the hidden enemies. Many deceived individuals provided clues, ensnaring the enemies in the people’s war.