Mark, who works in a nightclub in Los Angeles, U.S.A., and has always dreamed of becoming a world champion in an arm wrestling competition, is persuaded by Jin-gi, who identifies himself as his manager, to return to South Korea to compete in a national arm wrestling competition. In addition to the competition, Jin-gi gives Mark, who was adopted to the U.S. as a child, the address of his biological mother's house as a gift for his return home. However, Mark only meets his sister Soo Jin and her children, whom he has never met. With Jin-gi's help, Mark participates in an illegal arm wrestling competition. With the support of his family, can Mark fulfill his dream of becoming a champion in the face of the strong rivals of the arm wrestling monster?