The Red Sword tells the story of Wu Yuehua, a woman in cloth in Yan 'an, who was kidnapped and blackmailed by bandits in Cuijiagou in 1937. The security captain Yue sent a scout to solve the case. Cai Qin searched all the bandits who appeared near Yanchang County and found no clues. Cai Qin decided to catch the kidnapper by paying the ransom.
However, the final result is surprising. The kidnapper turned out to be Li Shili, a gentle Chinese teacher in Yanchang County. After the kidnapping of a civilian girl was detected, the public security environment in the border areas was greatly improved, but some bizarre incidents related to people's production and life in the border areas still occurred, such as the theft of weapons, the disappearance of side tickets and the disappearance of cattle.
Yue, the chief investigator, and Lu Fan, the deputy chief investigator, led a group of scouts to overcome many difficulties, uncover layers of fog, and finally successfully solve one case after another, making great contributions to defending border security and supporting the war of resistance.