Retired boxing champion Chen Zhendong is cheated out of a million yuan in profit-sharing by his nephew, Zhao Kai, who offers him nothing but a box of mooncakes. Furious, Chen quits and starts his own business. Due to Zhao Kai's poor management, a student suffers serious injuries and his boxing gym is shut down. Bitter and resentful, Zhao Kai and his father gather local thugs to vandalize Chen's gym in revenge. They also bribe a coach to drug and frame him. Relying on his genuine skills, Chen Zhendong opens his own combat sports club. At an international showdown, the 56-year-old knocks out a foreign fighter, clears his name, and ultimately brings the villains to justice, reuniting his family.