Based on the novel by Lloyd C. Douglas, the tribune who crucifies Jesus wins his robe on a bet and finds his life transformed along with those of his Greek slave, other Christians, and his childhood girlfriend.
In Rome’s slave market called Caligula’s Pavilion the tribune Marcellus Gallio (Richard Burton) helps catch the slave Demetrius (Victor Mature). Lydia complains about the drunken behavior of Marcellus. Diana (Jean Simmons) reminds Marcellus that they knew each other as children. Caligula (Jay Robinson) marches in with pomp and offers Marcellus a seat by him. Caligula outbids him for two female twins and gives them to Diana. Marcellus outbids Caligula for Demetrius, and Caligula is offended. Marcellus orders him unchained and sends him to his father’s house.
At home Marcellus learns that Diana may marry Caligula. He gets an order from Caligula to report to Jerusalem. Senator Gallio (Torin Thatcher) advises his son Marcellus to be a man of honor.
Marcellus and Demetrius board a ship. Diana tells Marcellus she is going back to Capri because she is still in love with him. He kisses her and asks her not to marry until he comes back.
Marcellus arrives in Jerusalem and is told about a coming messiah. They see Jesus riding into Jerusalem on a donkey, and Demetrius thinks he should follow him. At a bath Demetrius massages Marcellus. A centurion tells Marcellus he is supposed to arrest the messiah, and Marcellus has Demetrius give him his purse of money. Demetrius runs off to warn Jesus. Judas tells him that Jesus was betrayed and arrested.
A soldier wakes Marcellus and says Governor Pilate wants him. Demetrius asks Marcellus to intercede for Jesus. Pontius Pilate (Richard Boone) washes his hands and tells Marcellus he is to report to Capri, but first he must supervise the crucifixion. Marcellus rides a horse while Jesus carries the cross. Demetrius tries to stop a soldier from whipping Jesus and is knocked down. Demetrius wakes and walks up to the cross. He sees soldiers gambling and is asked to bring them the robe. Marcellus bets and wins it. A storm comes up, and blood drips on the hand of Marcellus. Jesus asks his Father to forgive them. In the rain Marcellus asks Demetrius for the cloth. When he puts it on, he shouts to take it off. Demetrius curses the Romans and leaves with the robe.
On a boat Marcellus is having a nightmare about the crucifixion. Marcellus arrives at Capri and kisses Diana. He says she has been with him since it happened; she is his one link with sanity. She embraces him, and he frees her from her promise. Diana asks Emperor Tiberius (Ernest Thesiger) to delay his audience with Gallio. Marcellus brings him dispatches from Pilate. Tiberius asks about Pilate, and Marcellus goes into a panic. He talks for two hours. The soothsayer says there is a curse on the robe, which must be destroyed. Tiberius orders Marcellus to get the names of the disciples. Tiberius frees Diana from Marcellus and lets her stay with him.
The Syrian guide Abidor (Leon Askin) in Cana tells Marcellus he has information for him. Marcellus buys cloth, and Justus (Dean Jagger) persuades people to give money back for overcharging him. Justus says his grandson Jonathan was crippled and healed. Marcellus gives Jonathan a donkey and learns Jesus lived near there. In the evening Miriam (Betta St. John) sings about the resurrection. Justus says she was a bitter cripple, but her attitude has changed. Marcellus says that Jesus is dead. Abidor says Pilate is offering gold for the Christians, and Marcellus gives him his purse.
In the morning Marcellus learns that Jonathan gave away the donkey. Miriam tells him what Jesus taught and that Peter is nearby. Marcellus finds Demetrius and orders him to burn the robe. Demetrius tells Marcellus his conscience made him afraid. Marcellus takes the robe and is no longer afraid. They meet Peter (Michael Rennie). Justus introduces Peter and is shot with an arrow. Marcellus tells the soldiers to stop it and learns that Caligula is emperor. Marcellus fights the centurion with a sword and wins but lets him live. The centurion orders the soldiers to leave.
Peter tells Marcellus that he is traveling with Demetrius and asks him to go with them. Peter says he denied Jesus three times. Marcellus says he crucified him. Peter says that Jesus forgave him. Marcellus enlists in his service.
Diana is summoned to Caligula, who asks about Marcellus. She says she has not got a letter since he was in Cana. Caligula says he is in Rome, and he is a dangerous traitor. He shows her Demetrius being tortured. Diana realizes that Marcipor is a Christian and asks him to take her to Marcellus, who asks her where Demetrius is. He organizes a rescue and kisses her. Marcellus says he is well and shows her the robe. She asks him not to risk his life for a slave; she wants to marry him.
Marcellus leads ten men into the palace. They overcome guards and free Demetrius. Angry Caligula says he wants Tribune Gallio. Soldiers search the home of Senator Gallio and leave. From a secret passage Marcellus and others carry Demetrius. The physician says he will die. Marcellus prays, and Peter comes in. Demetrius revives, and the physician calls it sorcery. Senator Gallio tells Marcellus that he is an enemy of Rome and no longer his son.
Marcellus takes Demetrius in a chariot, and they are chased by soldiers. Marcellus gets out to fight them while others take Demetrius to Peter. Diana visits Marcellus in a cell and asks him not to defy Caligula. Marcellus tells her about the believers in Cana.
Caligula asks Diana to sit by him. Caligula speaks about the Christian conspiracy and has Tribune Gallio brought in. He admits he is a Christian but denies they are plotting against the state. He says executing Jesus was Rome’s greatest mistake. Caligula asks about the robe and wants to destroy it, but Diana asks for it. Marcellus speaks about Jesus. Caligula asks for judgment, and Senators call for death. Caligula asks the Tribune to kneel and renew his loyalty. He does so and says he never broke it, but he refuses to renounce Jesus. Caligula orders him put to death. Diana asks to go with him because she will not live in his empire. They go together. Diana gives the robe to Marcipor, and they walk toward their kingdom.
This religious drama contrasts the power of imperial Rome with the spiritual message of the Christ. The spiritual power is conveyed in the robe of Jesus, and it stimulates people to face themselves and the truth about their life.