Opening in 1994, Knuckle City shifts between the childhood and adult lives of the sons (played as children by Inga Mtshizana and Elethu Mfombi) of legendary boxing champion turned gangster Art Nyakama (Zolisa Xaluva). Cut to 2019 and the boys have grown up to follow closely in the footsteps of their father. Dudu Nyakama (Bongile Mantsai) has become a womanizing professional boxer and Duke Nyakama (Thembikile Komani) is now a career criminal, chasing money and thrills at every turn. But Dudu is about to age out before he's had his chance at fame, and the fight promoters have a lot more faith in the young talent coming up behind him than they do in his comeback chances. With Duke set to be released after a three-year stint in prison, Dudu enlists the help of his brother's criminal connections to try to get himself one last shot - but both end up with a much bigger fight than they bargained for.