Jiang Xiezu is in love with Yang, a girl from the neighboring village, and they meet on a wooden bridge every night. Xiezu’s brother, Yaozu, who is a carpenter, repairs the bridge when it breaks and calls it the Younger Brother Bridge in memory of their fraternal affection.
Six years later, rebels begin to plague the country, and Yang and Xiezu lose touch with each other. The brothers seek refuge with their uncle, Tongxuan. Yang sells herself for the money needed to cure her ailing mother, and the brothers’ uncle buys her as a wife for Yaozu. On the wedding night, learning about the love between his younger brother and Yang, Yaozu writes a letter and leaves home. Abiding by his moral principles, Xiezu does not recognize Yang as his lover. Bully Jia Hua fails in his attempt to seduce Yang. Ganging up with Furong, a flirtatious maid in the uncle's household, the bully accuses Xiezu of having an affair with Yang. Yang pleads guilty to avoid implicating Xiezu and is sentenced to death.
Xiezu seeks his brother for help, but he is robbed on the way and loses his sight during the struggle. In despair, he returns to the Younger Brother Bridge to grieve over the good old days. It happens that Yang is to be executed that day. She is permitted to go to the bridge to bid a tearful farewell, and the two meet there. Soon, having found out what Furong has done, Tongxuan arrives to tell the truth. Yang is released and marries Xiezu.