At a party she is hosting, the courtesan Violetta Valéry is introduced to young Alfredo Germont. Violetta suddenly feels ill but assures her guests that she is fine. Alfredo, left alone with Violetta, confesses that he has loved her from afar for a year. She initially dismisses him, but is touched by his sincerity. After Alfredo and the other party guests leave, Violetta reflects on her feelings for him and on what life would be like if she accepted his love. But she cuts short her fantasy and rededicates herself to the pursuit of pleasure.
Act II / Scene 1
For three months, Violetta and Alfredo have been living together in the country. Alfredo learns that Violetta has been selling her possessions in order to pay their expenses, so he leaves for Paris to make other financial arrangements. Germont, Alfredo’s father, unexpectedly visits, demanding that Violetta leave Alfredo so that his sister’s impending marriage will not be threatened by scandal. Violetta first objects but finally, in spite of her love for Alfredo, promises to renounce him forever. She writes Alfredo a letter ending their relationship, but before she can depart, Alfredo returns and is confused by her agitated state. After Violetta leaves, he reads her letter. Germont returns and tries to comfort his son, but Alfredo decides to confront Violetta.
Act II / Scene 2
At a soirée given by Violetta’s friend Flora Bervoix, the guests are surprised by Alfredo’s arrival. Violetta soon appears with Baron Douphol, her new lover. Alfredo gambles with the gentlemen, pretending not to notice Violetta, who is alarmed by his belligerent behaviour. Fearing for his safety, Violetta begs Alfredo to leave, but he demands that she leave with him. When Violetta refuses, Alfredo summons the other guests and publicly humiliates Violetta. Germont arrives and denounces his son’s behaviour. The Baron challenges Alfredo to a duel.
Violetta is now gravely ill, and Dr Grenvil confides to Annina, her servant, that Violetta will not live much longer. Violetta rereads a letter from Germont informing her that Alfredo fled after wounding the Baron in the duel, but that he now knows of her sacrifice and is hurrying to her side. Alfredo arrives, begging Violetta’s forgiveness. The lovers dream of resuming their life together, but fate intervenes.