SETTING: Paris, 1850
At a party in Violetta's salon, Flora, the Marquis and the Baron arrive late, followed by Gastone and Alfredo. Gastone introduces Alfredo to Violetta and tells her that he visited her every day that she was ill. As all sit down to dinner, Gastone asks the Baron to propose a toast, but he refuses, while Alfredo accepts. Music is heard from another room and all are invited to dance. As the guests leave the room Violetta has a coughing attack. Alfredo remains behind and expresses his concern for Violetta's health, proclaiming that only he truly loves her. Violetta can offer only friendship and suggests that he won't find it difficult to forget her. As he starts to leave, Violetta stops him and offers him a camellia inviting him to come back when the flower has faded. The guests reenter and bid good night. Confronted with the power of his affection and commitment, Violetta considers if it is possible for someone like her to find true love. She dismisses the idea as ludicrous and proclaims she was meant for freedom and enjoyment.
Alfredo and Violetta have lived together for three months in a country house outside Paris. Alfredo's satisfaction comes from Violetta's abandonment of her former life to devote herself to him. Violetta's maid, Annina, greets Alfredo, and he asks where she has been. Though she has been sworn to silence, she tells him she has been to Paris selling Violetta's possessions. Alfredo resolves to fix the situation. He leaves, ordering Annina not to reveal his departure to her mistress. Violetta returns and receives an invitation from Flora to a party. Giuseppe then announces there is a gentleman to see her. The visitor reveals himself as Germont, Alfredo's father. He is concerned that his daughter cannot marry into the family she has chosen unless Alfredo gives up this current life. Germont wants her to give up Alfredo completely. She refuses, explaining that she has no friends and no relatives. She doesn't have a lot of time left. Eventually she gives in and asks Germont not to allow Alfredo to curse her memory and to tell him of her sufferings.
Violetta is writing a note as Alfredo enters. She hides the letter and Alfredo reveals that he is concerned that his father will visit them. Violetta confirms Alfredo's love for her and runs out. Alfredo's contentment is later disturbed when it is announced that Violetta has left for Paris and a letter is given to him that Violetta wrote earlier. He reads the letter and learns of Violetta's abandonment. As he turns to leave he runs into his father. Germont tries to comfort his son who is now full of vengeance. He sees Flora's invitation and realizes where Violetta has gone.
Later, at a party in Flora's salon, the Marquis informs the Doctor and Flora that Alfredo and Violetta have split and that Violetta will be coming to the party with the Baron. A group of party ladies enter disguised as gypsies, singing about telling the future. A group of men enter, led by Gastone, disguised as matadors and picadors. They sing of a brave matador who faced five bulls in a single day to win the heart of a young lady. All are surprised as Alfredo enters. He starts to gamble at cards. Violetta enters with the Baron. The Baron sees Alfredo, points him out to Violetta and warns her not to talk to him. Violetta agrees. Alfredo keeps winning at cards and recklessly announces that with his winnings he will go back to the country but not alone. The Baron challenges Alfredo to a card game. Alfredo wins. As supper is served, Violetta stays behind and asks Alfredo to slip away with her. She begs him to go away because he is in danger — the Baron might challenge him to a duel. He refuses unless she comes with him. She refuses, answering that she loves the Baron. Alfredo calls all the guests and humiliates Violetta by throwing the money he has won at her. The guests turn on him. Germont, who has arrived at the party and seen this display, asks if this is his son. Alfredo feels remorse immediately. Finally, the Baron challenges Alfredo to a duel for the offense as the other guests comfort Violetta.
Violetta is ill in her deserted home. When she awakens, she calls Annina, who apologizes for sleeping. Violetta wants to rise but she doesn't have the strength. The Doctor enters in time to help Violetta back to bed. He confides to Annina that Violetta has only hours to live. Violetta rereads a letter from Germont, which reveals that the Baron was wounded in a duel with Alfredo and that Germont has told his son everything about the departure of Violetta. Annina, hurrying into the room, prepares Violetta for a surprise. Violetta guesses the secret as Alfredo enters. He is ready to take her to the country. She gets up and starts to dress but is too weak. The Doctor enters, followed by Germont. Violetta tells Germont and his son that they have come too late. She then gives a miniature to Alfredo in order that he will remember her. Violetta has a moment of remission — no pain, no heaviness and a resurgence of strength. She collapses, and as Alfredo holds her, she dies.