[The film is loosely based on the book Satyricon attributed to Petronius Arbiter, and dated to the time of the rule of Nero (37-68 AD). The book is considered to be one of the first, if not the first, novels to have been written, but has only survived in fragments. The film imitates this by being fragmentary itself, leaving gaps between events, and even stopping in mid-sentence. However, there is a definite plot. Breaks in the plot representing the missing parts are given below with a double hyphen --]
The film opens with the protagonist Encolpio, a student, who is furious with his room-mate Ascilto, who has run off with their boy-slave Gitone. Encolpio tracks down Ascilto to the baths, and during a fight Ascilto admits to having sold the boy to Vernacchio who runs a theatre. Encolpio goes to the theatre and challenges Vernacchio during a performance, and gets the boy back through the intervention of a magistrate who is attending the play.
Encolpio and Gitone walk through the streets of Rome to go home. Seeing the magistrate has followed them and is beckoning to them, they dive into a brothel, and escape out of a back door, and then return to Encolpio's apartment. Ascilto returns too, and the two argue and decide to split up and divide their possessions. Gitone, allowed to choose who he goes with, chooses Ascilto. Only an earthquake saves Encolpio from committing suicide.
We find Encolpio in a museum, admiring the works. He bumps into an impoverished old man, Eumolpus, a poet, who is declaiming on the greatness of the classics and bemoaning the wretched state of modern art. Eumolpus takes Encolpio under his wing, and takes him to a feast at the villa of Tremalchio, a rich merchant despised by Eumolpus for his lack of culture. At the villa the guests are bathing before the meal, and Tremalchio seeing Eumolpus praises him as a colleague poet.
The guests enter the villa for the meal. During the meal the poet Eumolpus and the host Trimalchio become steadily more drunk, and in the end have an argument when Eumolpus accuses Trimalchio of plagiarism. Trimalchio orders his slaves to throw Eumolpus in the furnace, and a fierce fight follows in the kitchens.
Trimalchio gets morbid and takes his guests to the tomb where he will be buried when he dies. He bids everyone to act out his funeral. During the mock funeral a tale is told: a beautiful, newly-widowed woman decides to starve herself to death by her late husband's dead body in his tomb. A soldier who is guarding the bodies of recently executed prisoners, hears her wailing and goes to her. While they are together, the family of one of the executed takes his body, and when the soldier realises this he contemplates suicide as better than the punishment he will get. The widow however offers the body of her husband to hang up in the place of the criminal, to save the soldier's life.
Walking home after the feast, Encolpio finds the battered but still living Eumolpus. He stays with him, and they fall asleep by a lake.
Encolpio awakes, and to his shock everything has changed. He has been taken prisoner by Lichas, a treasure seeker who collects beautiful things and people and takes them to the sickly young Caesar who lives exiled on an island. Encolpio is bundled on to a ship, and sees that Ascilto and Gitone have been captured too.
During the voyage Lichas's eye falls on Encolpio, and marries him in a ceremony on the deck.
Meanwhile, the young Caesar is overthrown. A marauding party boards Lichas's ship, and kills him.
A war follows as the new Caesar takes power.
We see a man and his wife whose property is to be confiscated by the new Caesar sending their children off to safety. He frees his slaves, and waves his children goodbye, telling them he will see them soon. He then commits suicide, telling his wife not to do the same.
Later Ascilto and Encolpio creep onto the now-deserted property, and see the dead bodies of the man and his wife. They go into the house and explore, and discover a weeping slave girl. Seeing them she cheers up, and after a chase through the building, and a meal, the three spend the night together. They awake to the sound of burning. Looking out they see that the suicides have been put on a pyre by soldiers.
Ascilto and Encolpio are travelling with a caravan of people going to visit a hermaphrodite child demi-god at a temple. During an overnight stop they are told that one of the travellers is going because his wife has been beset with nymphomania and he hopes the god will cure her. But in the meantime he will pay them well if they will go and satisfy the wife.
The temple is a centre of pilgrimage for sick people wishing to be cured. The following night a man persuades Ascilto and Encolpio to help him steal the demi-god. They kill his keepers, and run off pulling the boy in a cart. However, the child cannot cope with the heat of the sun out of doors, and the next night dies. The man blames Ascilto and Encolpio and a fight ensues where the man is killed.
Possibly as a result of the theft, Encolpio has been captured, and is thrown into the Minotaur's labyrinth. If he defeats the Minotaur, his prize will be 'love'. He fails, but the minotaur is charmed by him and declares him a new friend, and refuses to kill him. As a result Encolpio may claim his prize, a session of passion with the beautiful Ariadne - in full view of the watching crowd. He approaches her, joins her on the bed, and discovers he has 'lost his sword'. Ariadne pushes him off in disgust and runs off.
And there is Eumolpus, now rich, and degenerate just like the Tremalchio he once so despised. He is a rich trader and his ship will be sailing again soon. He will help Encolpio restore his power, and suggests a visit to the Garden of Delights.
At the Garden of Delights, Encolpio fails to be cured. The curator there tells him the story of Oenothea, a woman who was cursed by a wizard for teasing him sexually, her punishment being literally fire between her thighs.
Ascilto and Encolpio travel to visit Oenothea. On the way the ferryman overhears that they have gold with them as payment. Oenothea cures Encolpio, but the ferryman fatally wounds Ascilto in a fight for the gold.
Mourning, Encolpio makes his way to the harbour where Eumolpus's ship will be sailing. But Eumolpus has died. He has left a will that frees his slaves, and grants his riches to those he mentions only if they will eat his body. Some agree to. Encolpio decides to sail with the ship in order to have more adventures.