The professional mercenary Sir William Walker instigates a slave revolt on the Caribbean island of Queimada in order to help improve the British sugar trade. Years later he is sent again to deal with the same rebels that he built up because they have seized too much power that now threatens British sugar interests.

Two Sicilian royalist soldiers flee the island in a trunk at the arrival of Garibaldi's republican troops. They end up in the Far West with the army fighting the Indians and with their ineptitude they contribute to the army's defeat.