As the prelude begins, Alfredo Germont reflects on his relationship with the courtesan Violetta Valery.

Violetta’s home in Paris. Violetta is hosting a party for her friends to celebrate her apparent recovery from an illness. Gastone introduces Alfredo to Violetta, explaining that Alfredo is a great admirer of hers. Violetta asks the Baron, her current companion, to offer a toast. The Baron refuses, so Alfredo leads the party-goers in song. The guests move into the next room, leaving an obviously unwell Violetta alone with Alfredo. Alfredo declares his love for her, but she tells him she will never allow herself to fall in love again. After the party, Violetta is surprised to find herself strongly attracted to Alfredo but resolves to continue her life of freedom and pleasure.

In the country outside Paris. Alfredo and Violetta have been living together happily for three months. Alfredo discovers that Violetta has been selling her possessions in order to finance their household and he leaves for Paris to raise money. Germont, Alfredo’s father, arrives unexpectedly and asks Violetta to end her relationship with Alfredo, since it jeopardizes his daughter’s upcoming marriage. Violetta eventually agrees and decides to return to her life as a courtesan. Alfredo returns and she reassures him of her love, even as she is departing for Paris. She leaves a note for Alfredo, informing him that she is returning to the Baron. Germont tries to reassure his distraught son, asking him to return to their home in Provence, but Alfredo vows revenge and leaves in pursuit of Violetta.

Flora Bervoix’s home in Paris. Alfredo arrives at Flora’s lively party. Violetta and Baron Douphol soon appear, having reunited. The Baron challenges Alfredo to a card game and loses a great deal of money. Alfredo tries to get Violetta to leave the party with him, but she refuses. Angered, Alfredo summons the party guests and throws the money he has won at Violetta’s feet. The Baron challenges Alfredo to a duel.

Violetta’s bedroom. Violetta is mortally ill. Both Germont and Alfredo travel to Paris in order to see her, but Violetta wonders whether she will live until their arrival. Alfredo rushes in and they declare their mutual love. Alfredo begins to describe a new life he has planned for them away from Paris, but it is obvious that Violetta’s death is imminent. Violetta gives her portrait to Alfredo, with the hope that he will find a “gentle maiden” to marry. After a final moment of strength, she dies.