 After the American Civil War, the half-breed Keoma (Franco Nero) returns to his homeland and rescues a beautiful pregnant woman accused of having plague, Lisa (Olga Karlatos), from a gang leaded by the landlord Caldwell (Donald O Brian). Later he meets his former slave servant and friend George (Woody Strode), now a drunk free man, and his father, William Shannon (William Berger), and he is informed that the town is under siege of Caldwell s men, without supplies of medicine or food and justice, with the dweller dying of plague and starvation and sick people is being isolated in an old mine. Further, his three dangerous half-brothers have joined Caldwell s force. Keoma decides to help Lisa and the dwellers to retrieve their freedom and dignity, and he finds how despicable the inhabitants are.