Randus (Steve Reeves) is the muscle-bound Roman legionnaire stationed in Egypt. The loyal soldier discovers he is the son of Spartacus, leader of a massive slave revolt. By day Randus is the faithful spear carrier, but at night he avenges the forces of evil by donning an iron mask and beating his enemies to a bloody pulp. He leaves the letter S carved on the chest of his victims to identify them as enemies against the rights of freedom. Eventually Randus is pardoned by the grateful Caesar when his efforts prove worthy of the Emperor's praise. He fights off treacherous soldiers and scheming opportunists who seek to overthrow the Emperor and go against the fortunes of Rome.