Former boxing legend Bernard 'Bang Bang' Rozyski (Tim Blake Nelson) lives in isolation, clinging to his violent and triumphant past. When his estranged daughter leaves her troubled teen son with him, Bang Bang sees a chance at redemption. As he trains his grandson in the ring, an old feud with a former boxing rival threatens to unravel everything. Can Bang Bang break the cycle, or is he passing down the same anger that once consumed him?