In Busan in 1978, Dongzhu (played by Zhang Dongjian) was a child from a poor family, and Junshuo (played by Liu Wuxing) was the son of the boss of a gangster group, the particularly diligent Shantai and the particularly eloquent Ronghe. Shantai often took the first place in the school, while Dongzhu and Junshuo were problematic elements who caused trouble everywhere, but the four of them were good friends. Dongzhu and Junshuo, who later entered middle school, were expelled from school for standing up for Shantai. In Seoul in 1984, Shantai and Ronghe, who entered university, searched for the whereabouts of two friends everywhere, but these two friends have now joined the underworld. One is in prison and the other is detoxifying. In the fall of 1990, Shantai, who studied in the United States, returned home for vacation, feeling the old friendship. Because of mutual revenge in gang fights, Dongzhu and Junshuo became real enemies. How should they face their former friends?