Act I

A late night party is in progress at the home of Violetta Valéry. Gastone presents to his hostess Alfredo, an admirer. It is soon learned that, while Violetta was recently taken ill, Alfredo visited her home daily for hopeful news of her recovery. Violetta retorts that it is more attention than she had received from her current protector, Baron Douphol, who is incensed by the behavior of the youthful upstart. When the Baron declines to make the evening toast, Violetta gives the honor to Alfredo.
    

As the guests retire to the ballroom, Violetta feels faint and rests for a moment. Alfredo lingers behind and soon professes his love for her. Friendship is all she can offer, but as he leaves, she gives him a flower from her breast and tells him to return when it has faded. As dawn approaches, the guests bid adieu, and Violetta reflects on the feelings Alfredo has aroused within her heart. She ponders whether or not she could ever give up her life of pleasure for true love.

Act II

 It is several months later, and Violetta and Alfredo are deeply in love. They have abandoned city life, taking residence in Violetta's country home. Alfredo soon learns from Annina that Violetta has had to sell many of her possessions in order to maintain their current lifestyle. Intending to set things right, Alfredo rushes back to Paris.
    

Violetta receives an invitation to a party that evening thrown by friend and fellow courtesan, Flora Bervoix. Violetta laughs at the notion of returning to her former life. She is then visited by Giorgio Germont, Alfredo's father, who rebukes her for ruining her son. Impressed by her graciousness in the face of his own rude behavior, Germont soon learns of Violetta's footing the bill and of how she intends to put her past behind. Still, he presses his case - his other child, a daughter, is about to marry but the union is in jeopardy as Alfredo's relationship with Violetta is causing a scandal for the family. It must be broken off.
    

Reluctantly Violetta agrees, but Germont must promise to one day tell Alfredo of her sacrifice. She responds to Flora's invitation, then dashes off a farewell note to Alfredo. Upon receiving the note, Alfredo is heartbroken and comforted by his father, who urges him to return to their home in Provence. Instead, an enflamed Alfredo pursues Violetta, suspecting she has returned to her former life and lover.

That evening at the party, Flora and her guests gossip over Violetta and Alfredo's recent split. After a brief diversion of dancing gypsies and matadors, Alfredo shows up unexpectedly. Violetta and the Baron arrive shortly thereafter, and Alfredo sends Violetta several bitter jibes, which enrages the Baron. He challenges Alfredo at the gaming tables, yet Alfredo is consistently the winner. As the guests retire to the dining room, Violetta pulls Alfredo aside and urges him to leave. He asks if she truly loves the Baron, and she continues her deception, saying yes. Alfredo calls everyone before him and throws his winnings at Violetta, declaring he has paid for her services in full. Giorgio Germont enters at that same moment and shames his son for the improper outburst. The Baron, demanding satisfaction for such an insult, challenges Alfredo to a duel.

Act III

Several months later, Violetta lies in her bed, desperately weak from the final stages of consumption. Doctor Grenvil attends her, but confides in Annina that the end is near. Violetta rereads a letter from Giorgio Germont – Alfredo wounded the Baron during the duel and was forced to go abroad. As promised, Germont told his son of her sacrifice, and he is hurrying back to beg her forgiveness. Violetta fears that he will not return in time, yet moments later he rushes to her side. Reunited, the lovers ecstatically plan for the future, and Violetta tries to rise but cannot summon the strength. As a last gesture of love, she gives Alfredo a miniature portrait of herself, saying that she will always be watching over him. Suddenly overcome by a euphoric feeling, Violetta cries out that she feels life returning, then falls dead in her lover's arms.