Guido Anselmi, a forty-three-year-old film director, visits a fashionable health spa, seeking treatment for his liver trouble. A number of people from the film industry, however, have followed him there in preparation for the production of his next film. On his first night, Guido has a dream in which he escapes from a car stalled in traffic and flies into the sky, only to be yanked back down to Earth by two film industry men. Guido wakes up as a doctor enters his room. During his physical exam, his collaborator and co-screenwriter Daumier enters and alludes to his displeasure with Guido’s work. Guido enters the bathroom for a moment alone, only to find a telephone ringing there.
At the spring of the health spa, the waters of which are considered an all-purpose “cure,” guests line up for glasses of spring water and relax in the garden. As Guido waits for his water, he has a vision of Claudia, his leading actress, but a plain-looking nurse wakes him from his reverie by telling him to take his glass of water. As Guido turns away from the spring, he again meets Daumier, who gives Guido a sheet of notes that criticize his script. In his tired, patronizing tone, Daumier lists the script’s faults and denounces the film for being uninspired. As Daumier drones on, Guido spots his old friend Mario Mezzabotta, who introduces him to his significantly younger American fiancée, Gloria Morin.
At a small train station, Guido reads Daumier’s notes as he waits for his mistress, Carla, to arrive. When the train comes, he thinks for a moment that perhaps Carla didn’t make the trip after all and feels relieved. He soon spots her on the other side of the train, however, burdened with an enormous cart of luggage. He takes her to a small family-owned hotel in order to avoid the attention that they would receive at his own hotel. When they arrive, Carla orders lunch, and as she enjoys a plate of chicken and chats about her husband, Guido becomes bored, reading a paper while he hums and smokes. Later, in Carla’s room, Guido directs a role-playing game in which he orders Carla to pretend she is a prostitute.
As Carla sits up in bed reading cartoons and eating peaches, Guido has an eerie dream in which he meets his parents in a graveyard. They both express disappointment in him, and after Guido helps his father step into a grave, he meets his mother, who suddenly transforms into his wife, Luisa, before he wakes up. Later, back at his hotel, Guido leaves his room and shares an elevator downstairs with clergymen. When he enters the lobby, a barrage of managers, actresses, and his collaborators demand his attention, and he dismisses each one as quickly as possible until he meets Pace, his producer, who gives him a watch as a gift.
Guido attends an evening entertainment revue at the hotel, where he watches Mezzabotta dance foolishly with Gloria. Bored with the music and irritated by complex questions that an American reporter asks him, Guido spots Carla, who sits at a far table in a failed attempt to be inconspicuous. A duo of mind-reading magicians begins its show, reading the minds of the hotel guests, and Gloria becomes frightened and refuses to participate. When the magicians read Guido’s mind, they produce the words Asa nisi masa, a mysterious and apparently nonsensical message that is significant in Guido’s past. The message causes Guido to recall a scene from his young boyhood, in his grandmother’s farmhouse, in which he bathes in a big tub with his cousins and is put to bed by his doting aunts and his grumbling grandmother. Guido’s young female cousin sits up in bed and tells him the words to a magic spell, Asa nisi masa.
At about two o’clock in the morning, Guido returns to the hotel lobby, where the concierge tells him that his wife, Luisa, telephoned. As he waits for the concierge to get her on the line, Guido talks with a French actress who has been trying desperately to find out more about her part in his film. He upsets the actress by refusing to give details about his film and saying he must leave to talk to Luisa. As they talk on the phone, Guido realizes how much he misses Luisa and asks her to join him at the spa. Before he retreats to his room, he visits the production office, where he answers the questions of his collaborator Cesarino, who is working on set details, and has a quarrel with his longtime friend and fellow director Conocchia, whom Guido accuses of being obsolete. Once in his own hotel room, Guido ponders the still-unfinished story of the film and has another vision of Claudia before falling asleep.
A ringing phone wakes him up a few hours later. It is Carla, calling from her hotel to ask him to attend to her because she has developed a fever. Guido goes back to sleep and doesn’t visit until the next afternoon. He finds Carla sweating and delirious, and he feels guilty for having dismissed her request. Later, he has a short meeting with the Catholic cardinal in order to discuss his film, but the cardinal asks him only whether he is married and whether he has children (he doesn’t). During the meeting with the cardinal, Guido’s attention is drawn to a woman some distance away, who reminds him of a gypsy woman, Saraghina, whom he knew in his youth. He then has a daydream about the day he and other Catholic schoolboys were caught watching Saraghina dance on the beach.
Guido has coffee with Daumier, who accuses him of being naïve, and then he visits the steam baths with his fellow filmmakers, Mezzabotta, and other familiar guests. Guido imagines the shrouded figures around him as expiring invalids and has a daydream about meeting the cardinal in a chamber of the steam baths. In this fantasy, the cardinal uses Latin passages of the Bible to instruct Guido to choose the path of the church.
That evening, Guido sees Luisa at an outdoor auction being held at the hotel. He watches her for a moment before she sees him, and they greet each other warmly. They dance together tenderly before Pace announces that they are going to visit the rocket launch pad that his construction team is erecting for the film set. Luisa suddenly becomes upset, perhaps by something that a member of the production team has told her, and refuses to sit with Guido on the drive to the set. As the group of filmmakers and their friends ascend the staircase of the launch pad, Guido consults with Rossella—his wife’s close friend—about Luisa, and Rossella tells him that Luisa is confused and dissatisfied with him. Guido confesses that his film doesn’t have anything to say, and Rossella tells him to make up his mind about his life. Back at the hotel, Guido and Luisa argue about his infidelity before going to sleep in separate beds.
The next morning, as Guido, Luisa, and Rossella have breakfast together, Carla arrives in a ridiculously embellished horse-drawn carriage and sits nearby. Guido pretends not to know her, but it is obvious to Luisa and Rossella that Carla is his mistress. Defeated, Guido retreats into a fantasy that takes place in the farmhouse of his youth, in which all the women to whom he has been attracted in his life devote themselves to his pleasure. At first, this harem seems harmonious, its women content with serving Guido. When an aging Parisian showgirl throws a fit because she is being sent upstairs (the place where women in the harem are banished upon reaching the age of thirty), however, Saraghina declares a rebellion, and Guido subdues them with a lion tamer’s whip.
Later that afternoon, Guido, Luisa, and their friends watch the screen tests with the production team. While Daumier alludes to Guido’s inferiority to the French novelist Stendhal, Guido fantasizes that Cesarino and his coworker Agostini hang Daumier. Luisa is furious to see that the mistress character and the wife character in Guido’s film are clearly modeled after Guido’s own mistress and herself. She walks out of the theater, and when Guido follows her, she says she is leaving him. Guido returns to the screen tests and reviews other actors who clearly represent his own real-life acquaintances.
Suddenly, Claudia Cardinale’s press agent appears to announce her arrival. Claudia takes Guido for a drive, asks about her part in the film, and expresses her enthusiasm about working with him. Finally seeing Claudia in the flesh, Guido finds her breathtaking yet disappointing. He knows that she will be neither the answer to the questions he has about his film nor the resolution for conflicts he wants to include in the picture. They park the car on a deserted road near the spring. Guido has one last vision of the ideal Claudia as the real version sits beside him and listens to his explanation of the film, which describes a man unable to commit to anything. Just as he admits to Claudia that there is no longer a part for her in his film, Cesarino, Agostini, Pace, and Conocchia arrive. They announce that there will be a press conference at the launch pad the next day and that shooting will begin in a week.
The next afternoon, droves of cars arrive at the launch pad. Agostini and Cesarino practically drag Guido to the press conference, and aggressive journalists shout questions at him all the way to the podium, where Pace insists that he give a speech. Overwhelmed by the pressure, Guido begins to hallucinate and sees Luisa in a wedding dress, asking him whether he will ever be faithful. Then, Guido imagines that Agostini puts a gun in his pocket, and Guido crawls under the table to shoot himself in the head.
Guido cancels production of the film. Agostini directs the construction crew to dismantle the rocket launcher, and Daumier, unusually supportive, congratulates Guido on having made the right decision to give up his mediocre film. As Daumier continues talking, Guido imagines that Maurice (the mind-reading magician) tells him that his show is just beginning. Guido sees Claudia, his aunts, Saraghina, his parents, Carla, the clergymen, and other familiar characters dressed all in white and blissfully smiling, walking together on grassy sand dunes. Guido is inspired once again and describes a new film that will portray his true self, no matter how confused it is. He asks Luisa to accept him as he is, and she says she will try.
Maurice and Guido direct all of the characters in the film into a large circle, which Guido persuades Luisa to join, then joins himself. The line moves off the stage, leaving only a boy fife player (who resembles Guido in his youth) who leads five circus musicians. The boy directs the other musicians to leave the stage before playing a short solo and marching out of the spotlight alone.