A murder investigation in Donghai City uncovers a larger conspiracy.

In 1936, the Long March of the Red Army passed through the Tibetan area by the Jinsha River. The Kuomintang colluded with the great local tyrant Qiu Wanli in an attempt to prevent the Red Army from crossing the river north. Qiu Wanli asks his minions to pretend to be the Red Army and rob the chieftain Sangge's only daughter Zhuma to provoke the relationship between the chieftain and the Red Army. The Red Army adhered to the party's ethnic policy, rescued Zhuma, and crossed the Jinsha River to the border of Tibetan areas. Qiu again sneaked into the Tibetan area. He said that Zhuma had been killed by the Red Army and provided ammunition and weapons for the chieftain to fight the Red Army. In order to expose the enemy's rumors, the Red Army instructor Jin Ming took a squad to escort Zhuma home.

A middle aged woman oculist has a heart attack. Recalling her past, she feels sorry for not having been a dutiful wife and mother, but she consoles herself with the thought that she has saved many people from blindness.