Wu Song was orphaned early and raised by his elder brother Wu Dalang. Mischance drove him away from his hometown. 

Years later, Wu Song returned to visit his brother.On the way he slayed a fierce tiger on Jingyang Ridge.His courage and valor won him the glorious title of “the Tiger-Killing Hero.”But his fate was reversed when he was introduced to Pan Jinlian, his sister-in-law.

Born to a poor family, Pan was sold to a rich man as a concubine.Her beauty made her a victim of envy, and she was married off to the dwarf Wu Dalang.Seeing the tall and muscular Wu Song, she fell immediately. 

Embarrassed by his rejection, she turned to the vile womanizer Ximen Qing.While Wu Song was away on duty, Ximen Qing had Wu Dalang poisoned.

Saddened and enraged, Wu Song presented his case to the county magistrate to demand justice.Yet, the biased and corrupt office denied him proper legal options.
Wu Song took the matters into his own hands and killed his sister-in-law at his brother’s vigil.He then hastened to the Lion Mansion to avenge his brother on Ximen Qing.

Thus, the “Tiger-Killing Hero” turned into a man-murdering criminal.Wu Song had no choice but to flee to Liangshan, where he became one of the 108 legendary “Outlaws of the Marsh.”