Rome since the time of Emperor Nero, mired in crime and debauchery. To Petronius - a writer, an esthete, a connoisseur of luxury and pleasure, "arbiter of grace", an approximate of Nero - is his nephew, a young and beautiful warrior, patrician Mark Vinicius. The young man says that, returning to Rome from the war against the Parthians, he injured his hand and, wounded, he was taken to his house by the gray-haired commander Avl Plavius. There Vinicius was captivated by a young Lygia, looking like a fragile dark-haired blue-eyed nymph. She is the daughter of the king of the Lygians, who live in the distant northern forests, and called her in the homeland of Kallina. As a child, she went to Rome as a hostage and grew up in the house of the noble Avl and his faithful, virtuous wife Pomponii. Treating Lygia as her own daughter, they raised her clean, chaste and not at all like dissolute Romans. They say that a young, beautiful, calm and sad Pomponia herself is a Christian, but Petronius, for example, does not believe in this: everyone knows that Christians are terrible villains, but Pomponia, whose face seems to radiate light, can never be a villain.

In the house at Avla, Vinicius uttered many fiery words to Lygia, and a reciprocal feeling flashed in the girl's heart. But for some reason she drew a fish on the sand ... Vinicius, who has lost his head, is ready to marry Lygia. But Petronius tells Nero that Vinicius fell in love with a skinny Ligi hostage. These words immediately avert the emperor himself from the girl - and he promises Petronius to take her to the palace and give Vinicius.

The giant and strong man Ursus accompanies Lygia into the palace, a Ligian who came to Rome with the little princess and, like her, who became a Christian here. In the evening, a girl trembling with fear is led to a feast. To the joy of Ligia, Vinicius takes the place next to her. Soon, intoxicated by passion and wine, he begins to passionately kiss the beauty, whispering that tomorrow Nero will give her to him. Ursus arrived in time and throws Vinicius away and takes the frightened girl out of the banquet hall.

Lygia is crying. She does not want to become a concubine of Vinicius. Better poverty than luxury and dishonor! Lygia decides to run.

Upon learning of the disappearance of Lygia, Vinicius in a rage kills the old slave, who nudged him. For the first time in my life, someone dared to oppose the desires of a young patrician! Maddened by love and despair, Vinicius searches for Lygia. Petronius, sympathizing with his nephew, is ready to give him his beautiful slave, the golden-haired Greek woman Evnika. But she so passionately prays not to send her out of the house, that the amazed Petronius understands: the girl is in love with himself! And the devotion of Evnika touches his heart. Evnika leads the cunning Greek Chilon - a drunkard and a red-faced, a con, a spy and a scammer who undertakes to find Lygia. Upon learning that the girl was drawing fish in the sand, this man, looking like a monkey and a fox at the same time, goes in search of.

He soon finds out that fish is a secret sign of Christians. Pretending to be a Christian, Chilon penetrates their environment and meets the doctor Glaucus, whose family at one time he gave out to robbers, and left himself to die on the road. Now Chilon is afraid that Glaucus will recognize him, and is trying to incite another Christian, the simple-minded strongman Urban, who says that Glaucus is a spy of the emperor, against the doctor. By the way the giant flinches when Chilo accidentally mentions the name of Lygia, the cunning Greek understands: Urban is Urs!

The Apostle Peter is in Rome. All the city’s Christians gather for his nightly sermon. Chilo leads there to Vinicius, who hopes to meet Lygia there. The Apostle Peter impresses the youth with simplicity and grandeur. The old man’s face shines with such conviction that is inherent in truth alone. But Peter's sermon is a denial of all the habitual life of Vinicius. However, the story of the crucifixion and resurrection of Christ astonishes the young patrician. And he suddenly realizes that the Christian Lygia will never become his concubine. Seeing Lygia in the crowd, Vinicius admires the spiritual beauty of the girl and realizes that against her faith all his strength and courage are nothing.

After leaving after the sermon after Lygia, Vinicius bursts into her home and tries to take the girl away, but Ursus brings down his powerful fist on the head of the patrician.

In the poor closet of Lygia, the healer Glaucus treats Vinicius. Lygia herself gently cares for the young man. He is happy; not wanting to leave his beloved, he decides to stay with the Christians and sends for Chilon - the only one who knows where Vinicius is now. Seeing Chilon, Glaucus recognizes in him the villain who has destroyed his entire family, and Ursus - the old man who set him on Glaucus. Chilo howls in horror, but the apostle Peter who appears appears lets the Greek go in peace: Glaucus and Ursus forgive their enemy ...

Shocked Vinicius reflects on the kindness and mercy of Christians. Then he falls into oblivion, and it seems to him that Lygia leads him to where the sun shines.

After a few days, Vinicius feels that his passion is being replaced by deep, true love. But the tormented Lygia, not daring to love the pagan with a wolf Roman heart, decides to part with the young man.

Vinicius returns to his house, but everything around him seems empty and insignificant to the young man. He longs for Lygia - and often recalls the amazing man he met with Christians - about Paul from Tarsus. “Each word turns him to dust all the foundations of our world,” the young man thinks. His soul is changing. He is now disgusted with the profligacy of the Roman nobility, and at a luxurious feast he rejects the harassment of the Empress Poppea. She disappears, laughing ominously. Vinicius dreams of Lygia. Suddenly, a tattered Chilo comes to him and declares that out of a passionate love for Christians he again tracked them all down. Enraged by the villainy of the Greek, Vinicius orders him to be carved; then the groaning Chilo leads the young man to the new home of the apostles. There Vinicius asks Peter and Paul for the hands of Lygia and promises that he will try to understand and accept the teachings of Christ. A happy Peter blesses lovers.

A distraught Nero dreams of a great fire - and soon the emperor’s minions set fire to Rome. Seeking Lygia, Vinicius desperately rushes about through the flames of the city. Having hardly got out in a smoldering tunic from a sea of ​​fire, the young man stumbles upon Chilo, who advises him to look for Lygia and Peter in one of the underground prayers of Christians. Vinicius hurries there and sees a lot of desperate people, whom the Apostle Peter calms with an affectionate word. Noticing Vinicius weakened from the experienced horrors, Peter leads him to Lygia. Having fallen to his knees, the young man warmly thanks the Lord, and Peter, whom Vinicius loved with all his unbridled heart, baptizes the young patrician in the poor hut of the excavator.

The people are bubbling with anger. To save the emperor and themselves, the patricians rumor that the city was set on fire by Christians. Karay "villains", Nero is going to arrange for the mob a spectacle that will be remembered for centuries. Poppea secretly leads to the emperor of Chilon; he is ready to betray all Christians - and above all, Vinicius with Lygia. Oh, Chilo will terribly avenge Vinicius for spanking!

Petronius warns his nephew that persecution of Christians is being prepared. With what pleasure the “arbiter of grace” will upset the plans of this monkey-Nero! But Vinicius does not have time to save Lygia: the girl is taken to prison. Petronius understands: this is the revenge of Poppea, which Vinicius rejected for the sake of Lygia. The young man, however, was not captured because they want to enjoy his suffering by torturing Lygia in front of him.

The mob is thirsty for blood, Christians thrown into prison - a thirst for martyrdom. The sufferings of Vinicius exceed human strength. And Saint Peter receives a revelation: in this city of Satan Christ wants to establish His capital!

With enlightened faces, Christians go to death - and in terrible agony they perish in the arena. Chilon, sitting in luxurious clothes next to Nero, whispers: "They see their resurrection!" - and falls without feelings. Executions continue. Vinicius, disguised as a grave digger, enters a terrible dungeon and spends three days with a sick Lygia. Their souls have already been cleansed of everything earthly. Vinicius firmly decides after the death of Lygia to admit that he is a Christian, and follow his beloved.

Christians are burned on poles, illuminating the emperor’s gardens with hundreds of living torches. From one of the pillars at the gray-haired Chilon, Glaucus, who was engulfed in flames, looks at him and wheezes: And the shocked Chilo, having turned from a miserable little man into a majestic old man, shouts: “Christians are innocent! The arsonist is Nero! ” These words are instantly spread throughout Rome, and Chilo, who repented of his sins, is baptized by the apostle Paul in a dark alley. Soon, Chilo is seized, but no torture can now force him to renounce his words. His tongue is pulled out and given to the bear to be torn to pieces in the arena. But the beast does not touch the unfortunate; with an enlightened face, the tortured Chilo gives up the spirit.

And the emperor decides to arrange Vinicia a "happy wedding." And as a chalk-white youth sees Ursa being pushed into the arena, and then they release a huge tour, to the horns of which the naked Lygia is tied. Urs grabs a tour by the horns and twists his neck. The audience roars with delight, and Nero, frightened by the crowd, gives Ursa and Lygia life and freedom.

In the house of Petronius, Ligius and Vinicius beg the suffering Peter to leave Rome. “I have to go after my flock,” the elder replies, but still the Christians manage to convince him that he must 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 are you going, Lord?” (Lat.)) - the apostle asks and hears the answer: “Once you leave my people, I go to Rome for a new crucifix”.

Shocked Peter returns to Rome. Soon the apostles are thrown into prison. But when they take the battered Peter to execution, he walks as a victor and, casting his eyes on Rome, whispers: “You are redeemed, you are mine!”

Paul is just as calmly going to execution on the same day. He knows that what he sowed will never dispel the whirlwind of malice.

Vinicius and his wife Ligia live peacefully in Sicily. They love each other, believe - and are immensely happy.

And Petronius is doomed. Nero plunges deeper into the vile profligacy, and the "arbiter of grace" now only interferes with the emperor. He is going to send Petronius a death sentence, but he decides to play the last joke with Nero. At a luxurious feast, surrounded by friends, to the enchanting music, he opens his veins. Along with him, the beautiful Evnika, who refused to live without a loved one, dies. Before his death, Petronius sends a mocking letter to Nero, in which he writes that he is ready to forgive the emperor for all crimes and murders, but deeply despises him for bad verses. The guests, looking at the beautiful marble-white bodies of the lifeless Petronius and Evnika, understand: the only thing left that remained of the old world is poetry and beauty.

Nero acts and goes wild. It seems that the world is turning into a continuous bloody and clownish orgy. Finally, the revolted legions proclaim Emperor Galbu. With the words: “What an artist dies!” Nero puts a knife to his throat, but is cowardly, and the slave helps his master to pass away with a short blow.

And from the soil, soaked in blood and tears, the seedlings of the seeds sown by Peter rise quietly, but steadily ...

Nero has long been a thing of the past, and the Basilica of Peter on the Vatican Hill reigns hitherto over Rome and the world. Near the ancient Kapensky Gate there is a small chapel with a half-erased inscription: “Quo vadis, Domine?”