Violetta Valery, a demimondaine, is giving a large reception. A friend, Gaston, introduces the young Alfredo Germont who is secretly in love with her and has come each day for news during her recent illness. Violetta ironically remarks to her protector, Baron Douphol, that he shows less interest in her than does this unknown young man. Alfredo proposes a toast. In an adjoining room dancing resumes, but Violetta, suddenly feeling faint, asks that she be left alone.

Alfredo nevertheless remains with her. He declares his love, but Violetta, though touched, does not seem to take him seriously. However, she gives him a flower and asks him to bring it back to her the next day when it has faded. The guests take their leave and, alone, Violetta admits to herself that she is troubled by this young man who has awakened within her dreams that have lain buried since childhood. But she pulls herself together: her destiny is not to live for the love of a single man and she must remain free to follow the paths of pleasure.  

First scene
Three months have passed. Violetta has yielded to Alfredo’s love and has taken refuge with him in a country house. Alfredo sings of his joy and happiness. However, he learns from Annina, Violetta’s maid, that her mistress must sell her assets to meet their material needs. He decides to go back to Paris to find the necessary money. Violetta is expecting her business advisor, but it is Giorgio Germont, Alfredo’s father, who makes an appearance. He speaks to Violetta coldly, convinced that the young woman is only interested in extracting money from his son.

His manner softens when he discovers the truth, but he still asks Violetta to renounce Alfredo. She refuses. Germont tells her about his daughter who is unable to marry because of her brother’s scandalous liaison. Understanding that her past will always dog her, Violetta yields, with death in her heart: she will leave Alfredo and take up her former life again. Germont takes his leave, moved by the nobility of the woman he has compelled to sacrifice herself. She prepares to write a farewell letter to her lover. She is interrupted by Alfredo’s return and leaves after bidding farewell to the young man who cannot understand.

He only realises upon opening the letter which Violetta has brought to him a few moments later. Germont returns and, not mentioning his visit to Violetta, tries to console his despairing son and praises the virtues of family life. But Alfredo’s only thought is to find Violetta again.

Second scene
The party is in full swing at the house of Flora Bervoix, a friend of Violetta’s. Alfredo appears. Flora is astonished to see him alone, but then Violetta makes her entrance, accompanied by Baron Douphol. Alfredo’s only desire is vengeance. He plays cards with the baron and wins a considerable sum.

Violetta is torn between the desire to explain and the promise she has made to Germont. Finally, she pretends that she loves Douphol. Mad with rage, Alfredo throws the money in Violetta’s face in front of all the guests, thus paying her for his three months of love. Violetta faints and the baron provokes Alfredo to a duel. Germont, who has followed his son, reproaches him for insulting a woman in such a way.

Violetta is seriously ill and abandoned by everybody. Only the faithful Annina remains at her side. The doctor comes to visit her as he does every morning and confides to Annina that Violetta has only a few hours to live. Outside, the streets of Paris echo to the sounds of the carnival. Germont has written to the young woman to tell her that Alfredo wounded the baron in the duel. He was obliged to go away, but his father has told him the truth and he is on his way back. Violetta awaits him desperately, even though she thinks it is now too late.

Alfredo finally arrives. He asks Violetta to forgive him. They will leave Paris again and she will recover her health. Germont also comes to visit the young woman, whom he now considers as his daughter, but she has no strength left. One last burst of vitality seems to bring her back to life before she collapses, dead.