Wu Dalang is Wu Song’s elder brother in Water Margin, a short, physically weak man who earns his living selling cooked cakes. He raises the younger Wu Song after their parents die, but the brothers grow into striking opposites: Dalang is cautious and vulnerable, while Wu Song becomes famous for killing the tiger at Jingyang Ridge. Dalang moves to Yanggu, marries Pan Jinlian, and runs his stall through the streets.
The household changes when Wu Song returns as a local constable. After Wu Song rejects Pan Jinlian’s advances and leaves on business, she begins an affair with Ximen Qing through Wang Po. A street boy named Yun’ge tells Wu Dalang, who goes to catch the pair. Ximen Qing kicks him in the chest, and the injured cake seller is carried home unable to defend himself.
Wu Dalang threatens to tell his brother when Wu Song returns. Pan Jinlian and Wang Po therefore prepare arsenic, force the poisoned medicine into him, and conceal his body beneath a blanket before arranging a quick cremation. He Jiu secretly keeps a bone as evidence. Wu Song later reconstructs the crime and avenges his brother. Wu Dalang has no martial equipment; his carrying pole, cake baskets, plain clothing, and street-vendor routine emphasize the ordinary life destroyed by people stronger and wealthier than he is.
