In the Salon in the house of Violetta Valéry, a fascinating and much-wooed courtesan in fashionable Parisian society, a sumptuous reception is in progress. Among the last guests to arrive, after gambling at cards in the house of Flora Bervoix, Viscount Gaston de Letorières introduces Violetta to Alfredo Germont, who is a fervent admirer of hers: so deeply in love, confides Gaston, that when she was recently ill he came each day to enquire secretly after her health. Violetta, touched by this unusual devotion, amiably dispels the young man’s shyness. Encouraged by his friends, Alfredo improvises a toast to beauty and to the joy of life. After supper, as the guests move off towards the ballroom, Violetta has a sudden fit of coughing. Alfredo, who is alone with her, begs her fondly to take more care of her health, assuring her that he would know how to look after her jealously. And tenderly he declares his love to her. Violetta is surprised and feigns indifference, replying that he will receive only friendship from her. Inwardly, however, she is perturbed by this confession. Plucking a flower from her bosom, she offers it to Alfredo for him to bring back when it has withered. Exultantly he takes it to mean an invitation to return the following day. Dawn has risen and the guests take their leave after the dancing. In solitude, Violetta ponders over Alfredo’s words of love. For the first time, someone has expressed a sincere affection for her. Accustomed to spend her life among fleeting joys and worldly pleasures, should she take him seriously, and change her way of life? No, she resolves not to pursue this foolish illusion. Though deep in her heart she feels that their love must be true.
In a country house near Paris Violetta and Alfredo are spending an idyllic life together, far from the social whirl of the capital. Alfredo expresses the fullness of his joy at this delightful situation, which has lasted now for three months. But the spell is unexpectedly broken by Annina, the maid, who tells him she has been to Paris upon Violetta’s orders, to sell jewels, horses and property to pay for the expenses of their stay in the country. Alfredo’s pride is hurted and he decides to leave at once in order to settle these affairs personally. Violetta enters. She is reading a letter from Flora, who has discovered the lovers’ retreat and invites her friend to a reception that same evening. Let her wait in vain, smiles Violetta. In the meantime a visit is announced. Giorgio Germont, Alfredo’s father, introduces himself to Violetta with a contemptuous air, convinced that the woman is being kept by his son. Proudly Violetta shows Germont the deed of sale of her estate. Germont is favourably impressed by this gesture. However he asks her on the strength of her affection, to renounce Alfredo in order not to ruin the happiness of another member of his family, his daughter, whose marriage with a young man «of good family» is liable to fall through unless her brother’s scandalous liaison is broken off. Violetta claims the rights of her love, telling Germont of her serious state of health, and desperately resists his pressing requests. But in the end she yields. In resignation she agrees to sacrifice her own happiness for the sake of Alfredo and his loved ones. She promises Germont, who is deeply moved, to face her immense sorrow alone and never to reveal to Alfredo why she has deserted him so precipitately. She is on the point of writing him a farewell letter when Alfredo himself appears and asks the reason for her strange uneasiness. Violetta answers with a heartrending cry of love, before hastening away. Later she sends him a note saying that she has decided to return to her former society life and old friends. Alfredo is deeply shaken. Germont arrives, but his fond words of consolation are of no avail, even though he reminds his son of the peaceful times spent in their native Provence, where he invites him to savour once again the warmth of family affection.
In a hall in the house of Flora Bervoix. A masked ball is in full swing. Violetta is in attendanceon the arm of Baron Douphol, her former protector. Not expecting to find Alfredo there,she is upset on seeing him, but he pretends to take no notice. He makes for the card tables, wherehe wins with shameless luck, while provoking Douphol’s resentment with vague allusions. The announcementof dinner prevents a quarrel, and the guests move into the dining room. Alfredo re-entersimmediately, having received an invitation from Violetta to talk with her. She implores him to leave and not to incur the baron’s wrath. Also, she confesses, if he would but realize, she fears most of all for his own life. But Alfredo replies that he will leave only if she will follow him. Violetta is compelled to reveal that she has sworn never to see him again. But since Alfredo insists on knowing who has had the right to impose this oath upon her, she allows him to understand that it was the Baron. Beside himself with jealousy and despair, Alfredo summons the guests. Confessing his shame at having allowed a woman to squander her fortune for him, he flings at Violetta’s feet a purse full of money, proclaiming that he has thus repaid her. Violetta faints, while Alfredo’s gesture is received with general indignation. Germont, who is arrived in the meantime, reproaches his already humiliated and repentant son, and drags him away, followed by Douphol who demands satisfaction for the insult to his partner.
Violetta, whose illness is by now beyond hope, is being looked after by the faithful Annina. It is a grey winter’s morning. Doctor Grenvil arrives and tries so instil hope and courage into his patient, but confesses to Annina that the end is near. Violetta once again re-reads the affectionate letter received from Germont, in which he thanks her for having kept her promise. He also informs her that the Baron was wounded in the duel and that he has at last revealed the truth to Alfredo, who is now on his way to visit her to beg forgiveness. A echo of carnival music and revelry rise from the street, Violetta gazes mournfully her pale image in the looking-glass and her heart breaks when she remembers the happy months spent with her lover. But now Annina enters to prepare her for a great emotion, followed at once by Alfredo, who throws himself into Violetta’s arms. Together they dream once again of a radiant future. Blissfully happy, Violetta would like to get dressed and go out into the festive city. But her strength fails her and she realizes she has not much longer to live. As Germont, who has joined his son, now clasps her to his heart like a daughter, she gives Alfredo a portrait of their happy years, begging him to keep it in memory of her who has loved him so deeply, and to offer it one day to the young woman who will be his future wife: on the stage Annina and Doctor Grenvil too. Suddenly she feels lifted by a mysterious force. Rising in one last longing for life, she falls back dead in Alfredo’s arms.