There is much talk in the small capital of an Italian province about the peculiar family arrangements of old Signora Frola and her daughter, the wife of Ponza, a newly appointed secretary to Commendatore Agazzi, the provincial councillor. Why is Signora Frola living by herself in a fine apartment next door to the Agazzis and not with her daughter and her son-in-law? Why are Ponza and his wife living in fifth-floor tenement rooms on the edge of town? Why does Ponza visit the old lady every evening and sometimes during the day, but always by himself? Why does Signora Frola never visit her daughter, and why does her daughter, whom no one except Ponza ever sees, never visit her? Why will the old lady not even permit Signora Agazzi and her daughter to pay a social call?

While the enigma is being discussed by Agazzi, his family, and several visitors in the Agazzi parlor, Signora Frola comes in to apologize for having refused to admit the Agazzis when they came calling and also to explain why she lives apart from her daughter. She does not want to interfere, she says, in the home life of her daughter and Ponza. She lives by herself, it is true, but she is not unhappy about it; she keeps in contact with her daughter, although there are no face-to-face visits.

Just after Signora Frola leaves the gathering in the parlor, Ponza—a fierce, nervous, sinister-looking man—comes in to explain about his poor mother-in-law. The truth is that she is mad, he says. Her daughter has been dead for four years, and he married again two years later. He has prevailed upon his second wife to humor the old woman by carrying on shouted conversations with her from a fifth-floor balcony and writing notes to be let down in a basket from the balcony to the old woman on the ground.

No sooner has Ponza gone than Signora Frola returns. Although the company at first denies it, she knows what Ponza has been telling them. The sad truth, however, is that he is the mad one. The real truth, which she wishes she did not have to tell, is that when he married her young and innocent daughter he so frightened her with his passionate attentions that she had to be put into an institution for a while. When she finally returned, Ponza himself was in such a nervous state that he could not be convinced that she was his wife; she was prevailed upon to pretend that she is a second wife taking the place of the one he lost.

Before long, a plot is hatched to have Signora Frola and Ponza confront each other in the presence of Agazzi and the others in order that the truth might be uncovered. From the beginning of the gossipy, inquisitorial discussion, Lamberto Laudisi, the brother-in-law of Agazzi, has maintained that the private domestic lives of the Ponzas and Signora Frola are their own affair and should remain so. They are harming no one, and they are not seeking anyone’s aid; they should be left alone. Laudisi is overruled, however. Agazzi leaves and comes back shortly to get some papers that he purposely left in his study so that he might bring Ponza back with him to get them. As they come in, Ponza hears a piano in the next room playing a tune that had been a favorite of his wife, Lena. Signora Frola is playing the piano; when she stops, her voice can be heard through the doorway. She is discussing her daughter’s cherished melody in such a way as to suggest that Lena is still alive. When she confronts Ponza a moment later in the study, he furiously insists that Lena is dead, that he is now married to Julia, and that the piano that Lena used to play was smashed to pieces long ago.

While Ponza is shouting at her in a frenzy, Signora Frola occasionally glances about at the others in the room as if to call attention to his piteous state and to her forbearance in humoring him. After bursting into tears, Ponza suddenly orders her out of the room, and she soon leaves, also sobbing. When she has gone, Ponza immediately grows calm again and explains the reason for his actions. The old woman, he says, is so convinced of his madness that he has to pretend to be mad. Now he must go and see her. Laudisi, who had earlier insisted that truth is a relative thing and that what is one person’s truth is not necessarily another’s, laughs at the confusion of the Agazzis and their visitors. Now, he mocks, they have the truth they wanted.

Still the puzzle remains: Who is telling the truth and who is lying, either knowingly or unknowingly? Earlier, someone had suggested that documents, such as a marriage certificate for the second marriage or the letters that the second—or first—Signora Ponza wrote to the old woman, might be secured to prove who is right. One of those interested, Commissioner Centuri, arrives with some information that he has uncovered that might yet clear up the puzzle, but the information turns out to be as inconclusive as that already at hand.

A chance remark that Signora Ponza might as well be in another world, since no one has ever seen her, makes Laudisi wonder whether there really is a Signora Ponza. It is then suggested that Ponza go and get his wife so that she might be seen by everybody, to prove that she exists, and that she be questioned by the prefect in the presence of everyone so that the truth might be generally known. Ponza leaves after he has been assured that his wife and his mother-in-law will not be compelled to face each other. In his absence, the old woman returns to say that, since she cannot live her own life in peace, she will leave town and not come back. To pacify her, the prefect pretends to believe her version of the truth, although he earlier said he believed Ponza’s. When Ponza returns with a heavily veiled woman dressed as if she were in deep mourning, he is shocked and angry to see his mother-in-law there, given that he had been assured that she would not be present. Signora Ponza, to quiet the clamor, asks Ponza to take the old woman away. Ponza and his mother-in-law go out weeping and with their arms about each other’s waists.

Now the truth will finally come out: Signora Ponza will tell the entire group the whole truth. For the final time, however, the decision is left to each of her hearers. She is, it seems, the daughter of Signora Frola; she is also the second wife of Ponza; and, for herself, she is nobody. When the prefect insists that she must be one or the other of the two women, she answers that she is the person she is believed to be. Hearing that reply, Laudisi, saying that everybody now knows the truth, bursts out laughing.