Act 1
The action of An Ideal Husband takes place within about twenty four hours. Act 1 takes place at Sir Robert Chiltern’s house, which is located in the fashionable part of London. The Chilterns are hosting a reception. The first two speakers of the play, two minor characters, Lady Basildon and Mrs. Marchmont, set a witty tone. They are pretty, young married women, and they speak to each other languidly and cleverly. Attention then moves to various new arrivals at the reception, such as the Earl of Caversham, who inquires after his son Lord Goring, and Mabel Chiltern, Sir Robert Chiltern’s sister, who chats with the Earl of Caversham. The most important arrivals, however, are Lady Markby and Mrs. Cheveley, because the latter is the play’s villain.

That something serious will be occurring in this otherwise comic play becomes clear when Lady Markby introduces Mrs. Cheveley to Lady Chiltern. Lady Chiltern realizes that she knows Mrs. Cheveley, but under a different name—the name of her first husband. Mrs. Cheveley clearly disturbs Lady Chiltern, and Lady Chiltern appears to dislike the other woman intensely.

Mrs. Cheveley has come to the party to speak to Sir Robert specifically, and, soon enough, the two find themselves alone. What she wishes to talk about is blackmail: if Sir Robert does not support what is in fact a doomed South American canal scheme in a speech to the parliament the next day, she will reveal the terrible secret of his youth, which will destroy his life and career. Shaken to his core, Sir Robert agrees to do her bidding.

At the end of act 1, Lady Chiltern succeeds in getting her husband to admit that Mrs. Cheveley has persuaded him to change his mind about the canal project. She is outraged and convinces her husband to write to Mrs. Cheveley immediately, telling her that he will not support the project in his parliamentary speech. Wondering what kind of power Mrs. Cheveley has over her husband, Lady Chiltern declares that it had better not be blackmail—that he better not be one of those men who pretend to be pillars of the community but who in fact have shameful secrets.

Act 2
Act 2 opens the next morning, once again at the Chiltern residence. Lord Goring and Robert Chiltern are speaking; Chiltern is telling his good friend Goring everything. At one point, Chiltern bitterly wonders why a youthful folly has the power to ruin a man’s career, even when that man has spent so many years doing good works. To this Goring replies that what Chiltern did was not folly but fairly ugly and very grave: he sold a state secret for money.

Chiltern tries to explain, saying that when he was young he was poor, so that it did not matter that he came from a good family because his prospects were limited by a lack of funds. He tells how he was seduced by the teachings of Baron Arnheim, who turned his head with ‘‘the most terrible of all philosophies, the philosophy of power.’’ The baron ‘‘preached to [him] the most marvelous of all gospel, the gospel of gold,’’ he says. Chiltern says he was ferociously ambitious, and that when the chance came to make his fortune, it did not matter that it depended on a crime; he took it.

Lady Chiltern comes home while the men are conversing. She has been at a ‘‘Woman’s Liberal Association’’ meeting, where, as she says, they discuss things such as ‘‘Factory Acts, Female Inspectors, the Eight Hours Bill, the Parliamentary Franchise,’’ and so on. Soon, Robert Chiltern leaves and Mabel Chiltern takes his place, asking Goring if he will meet her the next morning. Goring agrees and then leaves. Next, Lady Markby and Mrs. Cheveley are announced. Mrs. Cheveley is inquiring about a diamond broach she lost the day before, asking whether it was found by anyone at the reception. (Lord Goring found the broach and still has it.)

When Lady Markby leaves, Lady Chiltern and Mrs. Cheveley are able to speak to each other frankly. Lady Chiltern makes it clear that Mrs. Cheveley is not welcome in her house. This spurs Mrs. Cheveley to tell Lady Chiltern the truth about her husband, and she warns Lady Chiltern that she will carry out her threat. Lady Chiltern is devastated to find out that her husband is like so many other men, men who have shameful secrets. She confronts her husband and tells him that her love for him is dead.

Act 3
Act 3 takes place in Lord Goring’s house, in the library, which is connected to a number of other rooms. Lord Goring is preparing to go out for the evening when he receives a letter from Lady Chiltern. It reads, ‘‘I want you. I trust you. I am coming to you.’’ Goring rightly deduces that Lady Chiltern now knows the truth about her husband and that she needs to talk to someone.

Goring cancels his plans to go out and realizes that he must tell his servants that he is not in for anyone except Lady Chiltern; it would be disastrous for her reputation if she were found in his home without a chaperon. However, before he can do this, his father is announced. Unfortunately for Goring, his father is in the mood to lecture him. Goring tries unsuccessfully to get rid of his father and must listen to him go on about Goring’s need to marry and settle down. In the meantime, Mrs. Cheveley has arrived, and a servant, thinking she is Lady Chiltern, escorts her into Goring’s drawing room.

Finally able to show his father the door, Goring is put out to find Sir Robert Chiltern on his doorstep. Goring tries to get rid of Chiltern, believing all the while that Lady Chiltern is in the next room. He is concerned that Chiltern will discover his wife and misconstrue her presence in his home. Chiltern lingers and eventually overhears a sound coming from the room in which Mrs. Cheveley is waiting. He goes in, sees the woman, and returns to Goring disgusted. He believes that Mrs. Cheveley and Goring are having an affair. Goring, for his part, believes that Chiltern has just seen his own wife. Chiltern leaves and Goring sees that it is Mrs. Cheveley who is in the room.

Lord Goring has Mrs. Cheveley’s diamond broach and tells her that the broach was a gift he gave to his niece, so that the only way Mrs. Cheveley could have come by it was to have stolen it, which she did. He threatens to call the police and have her prosecuted for theft unless she drops her blackmail plans. She has no choice but to concede, and Goring makes her hand over the letter Chiltern wrote all those years ago. Goring burns the letter.

Act 4
Act 4 is the resolution of the play. It takes place in the morning room of the Chiltern residence, the same setting as act 2. Lord Goring finally realizes that Mabel Chiltern is the woman for him and proposes. Mabel is very happy, as is the visiting Earl of Caversham. Lady Chiltern has forgiven her husband but still believes he must give up public life. She thinks they should retire to the country. Lord Goring convinces her otherwise. He makes her see that her husband thrives on politics, and if she were to take that away from him, he would become bitter and disillusioned and their marriage would suffer. Lady Chiltern realizes that Goring is right and relents. Sir Robert is ecstatic.