A family is persecuted by I-Kuan Tao, a feudal religious organization.

During the early War of Resistance Against Japan in Baiyangdian, Hebei, the Yanling Squad, led by Communist Party member Hei Lao Cai, conducted effective guerrilla warfare. Yang Xiaomei, fleeing abuse from her husband Zhang Jinlong, joined the squad and developed feelings for farmer Niu Dashi. Zhang Jinlong, unable to change, defected to the Japanese. As Japanese sweep operations intensified, Xiaomei, Dashi, and Zhang Jinlong faced different paths in the conflict.

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.

Occurring at the time of the Chinese Civil War, following the victory over Japan, Nationalist agents fail in trying to destroy the student movement in Beijing.