Rome of Emperor Nero’s times is steeped in crime and debauchery. Marcus Vinicius, a young and beautiful warrior, come to his uncle Gaius Petronius, who is a writer, aesthete, connoisseur of luxury and pleasure, and the approximate of Nero. The young man says that, returning to Rome from the war against the Parthians, he injured his hand and, wounded, has been taken to the house of the white-haired commander Aulus Plautius.
There Vinicius has been captivated by a young Ligia, a daughter of the king of Ligians, who lived in far northern forests. At home they called her Galina. As a child she came to Rome as a hostage, and grew up in the house of the noble Aulus and his faithful, virtuous wife Pomponia. Treating Ligia as their own daughter, they raised her pure and chaste, she was nothing not like debauched Roman women. Pomponia is said to be a Christian, but Petronius does not believe it, as Christians are said to be terrible villains, and Pomponia’s face seems to radiate light, and cannot be villain in any way.
In the house of Aulus Vinicius he uttered to Ligia many fervent words, and the girl's heart burnt with reciprocal feeling. Vinicius is ready to marry Ligia. He does not understand the only thing – why she is drawing a fish on the sand. Petronius tells Nero that Vinicius fell in love with weedy hostage-ligian, and the Emperor promises to Petronius to take her to the palace, and to give Vinicius.
Ligia is accompanied to the palace by a giant Ursus, a ligian who came in Rome together with a little princess, and, as she has become a Christian here. In the evening, trembling from fear she is led to the feast. Fortunately, Ligia takes place next to Vinicius. Soon, intoxicated with wine and passion, he began passionately kissing a beautiful woman, whispering that tomorrow Nero would give her to him. Ursus came to the rescue throwing Vinicius away and taking a scared girl from banqueting halls. Ligia is crying. She does not want to become the concubine of Vinicius. Better poverty than luxury and dishonor! Ligia decides to run.
After learning about the disappearance of Ligia Vinicius kills the old servant. For the first time in his life someone has dared to oppose the wishes of the young patrician! Mad with love and despair Vinicius is looking for Ligia. Petronius, sympathizing with his nephew, is ready to give him his beautiful slave girl, golden-haired Greek Eunice. But she so passionately pleads not send her out of the house that Petronius realizes she is in love with himself. And Eunice’s devotion touched his heart. Eunice brings crafty Greek Chilo – a drunkard, swindler, a spy and informer, who gets to find Ligia. Upon learning that she drew a fish on the sand, this man, like a monkey and the fox at the same time, goes in search of her.
He soon discovers that the fish is a secret sign of Christians. Pretending to be a Christian, Chilo penetrates into their environment and meets the physician Glaucus, whose family at one time he gave up to the robbers. Now Chilo is afraid that Glaucus would recognize him and tries to incite on the physician another Christian, simple-minded strongman Urban telling him that Glaucus is Emperor’s spy. By the way the giant shudders when Chilo accidentally mentions the name of Ligia, cunning Greeks understood that Urban is Ursus.
The apostle Peter comes to Rome. To his sermon at night all the Christians of the city are going to. Chilo brings there Vinicius, who hopes to meet there Ligia. The apostle Peter struck the boy with his simplicity and grandeur. His face is lit with such a power of persuasion, which is inherent only to truth. But Peter's sermon is the negation of all the usual Vinicius’s life. However, the story of the crucifixion and resurrection of Christ shakes the young patrician. And he realizes that Christian Ligia would never be his concubine. When he saw Ligia in a crowd, Vinicius is admiring the beauty of the girl and realizes that his strength and courage against her faith is nothing.
Having followed Ligia after the sermon Vinicius burst into her home and tries to carry her, but Ursus brings down on patrician’s head his mighty fist. In the poor closet of Ligia Glaucus is looking after Vinicius. Ligia herself tenderly cares for him. He is happy; not wanting to stay with his beloved, he decides to stay with the Christians, and sends for Chilo - the only one who knows where he is. After seeing Chilo, Glaucus recognizes him as the villain who had destroyed his whole family, and Ursus the old man who incited him on Glaucus. Chilo is howling with terror, but there appears the apostle Peter and lets the Greek go, Glaucus and Ursus forgive their enemy.
Shaken Vinicius is pondering over kindness and charity of Christians. Then he falls into oblivion, and he fancies that Ligia leads him to the place where the sun shines.
A few days later Vinicius feels that his deep passion is replaced by true love. But torn Ligia, not daring to love a pagan Roman with wolf heart, decides to leave the boy.
Vinicius returns home, but everything seems to be empty. He yearns for Ligia, and often reminisces about the wonderful man he met the Christians, - of Paul from Tarsus. His soul is changing. He considers debauchery of the Roman nobility disgusting, and at a luxury feast he rejects harassment of Empress Poppaea. She disappears laughing sinisterly. Vinicius dreams of Ligia. Suddenly ragged Chilo comes to him and says that once again tracked the Christians. Enraged by meanness of the Greek Vinicius orders to whip him; then moaning Chilo leads young man to the new home of the apostles. There Vinicius asks Peter and Paul for Ligia’s hand and promises that he will try to understand and accept the teachings of Christ. Delighted Peter blesses the lovers.
The maddened Nero is dreaming about the great fire - and soon the Emperor's henchmen set fire to Rome. Looking for Ligia, Vinicius, in despair rushes by the city in flames. With difficulty clambered into smoldering tunic from the sea the boy stumbles on Chilo, who advises him to seek Ligia and Peter in one of underground chapels of Christians. Vinicius hurries back and sees a lot of desperate people being calmed down by the tender words of the Apostle Peter. Noticing weakened from the horrors Vinicius, Peter leads him to Ligia. Falling to his knees, the young man warmly thanks the Lord, and Peter, who loved Vinicius with all his heart, baptizes a young patrician in a poor hut of a digger.
People are overfilled with anger. To save the Emperor and themselves the patricians rumor that the Christians had set fire to the city. Punishing the "evildoers" Nero was going to arrange spectacle that would be remembered for centuries. Poppaea secretly leads Chilo to the emperor; he is ready to give up all the Christians - and especially Ligia and Vinicius. Chilo takes his revenge for being spanked.
Petronius warns his nephew that the persecution of Christians is being prepared. But Vinicius does not have time to save Ligia: she is taken away to prison. Petronius understood: this is revenge of Poppaea, whom Vinicius rejected for Ligia. He himself was not arrested because they wanted to enjoy his suffering, torturing Ligia in front of his eyes.
The mob is engulfed with bloodlust; thrown into prison Christians - with a thirst for martyrdom. The suffering of Vinicius exceed human forces. And St. Peter receives a revelation: in this city of Satan the Christ wants to establish his capital!
With enlightened faces the Christians are going to death and in terrible pain die in the arena. Chilo sitting in luxurious robes next to Nero, is whispering, "they see their resurrection!" and falls unconscious. Executions continue. Vinicius, disguised as a gravedigger, gets into a terrible prison and spends three days with Ligia. Their souls have been cleansed from all the earthly things. Vinicius decides after the death of Ligia to admit that he is a Christian, and to follow his beloved.
Christians are being burned on poles covering with hundreds of live torches the emperor’s gardens. On one of the pillars Glaucus looks at the grizzled Chilo and croaks: "I forgive!" And shocked Chilo, turning from a miserable man in the grand old man shouted: "Christians are innocent! Nero is the incendiary”. These words instantly are spread over Rome, and repented of his sins Chilo is being baptized in a dark alley by the apostle Paul. Chilo is captured soon, but no torture can force him to recant his words. They ripped off his tongue and let him be torn on the arena by bear. But the beast does not touch the accident; with enlightened face tortured Chilo emits spirit.
And the emperor decides to give Vinicius a "merry wedding." And white as chalk boy sees Ursus pushed in the arena, and then a huge tour, to whose horns naked Ligia is tied. Ursus grabs the tour’s horns and cracks his neck. The crowd roars with delight, and Nero, fearing the crowd, gives Ligia and Ursus life and freedom.
In the house of Petronius Ligia and Vinicius beg long-suffering Peter to leave Rome. "I must go after my flock," – he says, but still Christians manage to convince him that he should sow the seeds of truth in other cities and towns. And Peter leaves Rome - but on the Appian Way Christ appears to him. "? Quo vadis, Domine" ("Where do you go, Lord?" (Latin).) - Asks the Apostle, and hears in reply: "If you leave my people, I am going to Rome for a new crucifix."
Shaken Peter returns to Rome. Soon the apostles are thrown into prison. But when Peter is beaten to death, he walks like a winner, and, looking around Rome, whispers, "You are redeemed, you're mine!"Equally quietly Paul goes on the same day at the penalty.
Vinicius and his wife Ligia live peacefully in Sicily. They love each other, they believe, and are immensely happy.
But Petronius is doomed. Nero is sinking deeper into the infamous lewdness, and Petronius now only prevents the emperor. He's going to send Petronius death sentence, but the last decides to play with Nero his last joke. On the feast of luxury, surrounded by friends he opens his veins. With him dies beautiful Eunice, refused to live without a loved one. Before his death Petronius sends Nero a mocking letter in which he had written that was ready to forgive all offenses and murder, but deeply despised him for his bad verses. Guests looking at a beautiful marble-white lifeless bodies of Petronius and Eunice, understand that the only thing that still remained in the old world - poetry and beauty, has been killed.
Nero becomes completely mad. Finally, mutinous legions proclaimed Galba the emperor. With the words: "What an artist dies!" Nero puts the knife to his throat, but cannot do it because of fear, so his slave with a short stroke helps his master to die.
And from the soil soaked with blood and tears, quietly but steadily rise up the seeds sown by Peter.
Nero has long been left in the past, and Peter Basilica at the Vatican hill until now reigns over Rome and over the world. Near the ancient Porta Capena stands a small chapel with partly vanished inscription: "Quo vadis, Domine?"