Mu Hong, nicknamed the Unrestrained, is the wealthy elder son of the Mu household near Jieyang in Water Margin. He and his younger brother Mu Chun command local influence that can turn quickly into violence. When Song Jiang supports the traveling performer Xue Yong against Mu Chun, the brothers pursue the stranger without knowing who he is. The chase drives Song Jiang toward Zhang Heng’s lethal ferry and nearly turns several separate Jieyang factions against one another.
Li Jun arrives on the river, recognizes the famous exile, and transforms the encounter. Once Mu Hong learns that the hunted man is Song Jiang, hostility becomes hospitality and lasting allegiance. That allegiance is tested at Jiangzhou: Mu Hong joins the rescue force that fights to save Song Jiang and Dai Zong from execution. He then burns the family estate, gathers the household and its wealth, and gives up the protected life of a local magnate for Liangshan’s collective cause.
At the grand assembly Mu Hong ranks twenty-fourth as the Heavenly Ultimate Star and holds one of the Eight Tiger Cavalry vanguard posts. The high position reflects status, resources, and sustained mounted service rather than one legendary duel or named weapon. He survives many of the campaigns after amnesty but is defeated by disease rather than steel during the war against Fang La. Left at Hangzhou for treatment, he dies before the army’s return. His arc moves from coercive local power to costly loyalty: the man who first hunts Song Jiang ultimately abandons his estate, fortune, and safety to follow him.