The movie is introduced by the closing scene from the previous year's The Robe, in which Marcellus (Richard Burton) and Diana (Jean Simmons) are martyred for their Christian beliefs. As they are led away to their deaths, the robe of Christ is given to former slave Demetrius (Victor Mature) for safekeeping. Mad emperor Caligula, mistakenly believing that it is the mysterious robe which bestows eternal life, orders his soldiers to find it at all costs. While ransacking the village of Demetrius during the search, a Roman soldier assaults Lucia (Debra Paget), the beautiful love interest of Demetrius. Demetrius rushes to her defense and attacks the centurion. He is sentenced to a gladiator school, where he draws the lustful attention of sensuous Messalina (Susan Hayward), the unsatisfied wife of Caligula's elderly uncle. Demetrius initially refuses to fight out of devotion to his Christian beliefs. But when he spurns the advances of Messalina, she is enraged and wants revenge. He is returned to the arena where he is forced to defend himself against several tigers, killing all of them. He becomes a hero to the crowds. Lucia goes to the gladiator school to see Demetrius, but Messalina allows her to fall into the hands of the gladiators. As one of the gladiators hungrily paws at her, a helpless Demetrius prays for her deliverance. She fights wildly before falling into a catatonic state resembling death. An embittered Demetrius renounces his faith and accepts a post as a centurion. Caligula sends Demetrius to the Christian enclave to personally find the robe, where he finds unconscious Lucia clutching the sacred robe. The emotional encounter sets him on the path to redemption.