The play takes place throughout the day in London, in the mansion of the Chilterns' couple and in the apartment of Lord Goring, in the early 1890s.

The evening in the octagonal hall of the mansion of Baronet Sir Robert Chiltern, who holds the responsible post of Comrade Minister of Foreign Affairs, is one of the most exquisite attractions of high society London. The refined taste of an exemplary couple is reflected in everything - from the paintings of Boucher and Corot on the walls to the appearance of the owners of the house and guests. Such is the mistress of the house, the twenty-year-old Gertrude - “a type of strict classical beauty”, the young sister of Sir Robert Mable - “the perfect example of English female beauty, white and pink, like the color of an apple tree”. To match them, and Mrs. Cheavley - "a work of art, but with traces of too many schools." Characterizing the characters of the stronger sex, the playwright also does not miss the chance to notice that the elderly dignitary, Lord Goring’s father, Lord Caversham “resembles a portrait of Lawrence’s brush”, and speaking of Sir Robert himself, add that “Van Dyck would not refuse to paint his portrait.”

The attention of the secular nobility is attracting a new face: in the company of the elderly good-natured lady Markby, a certain Mr. Chivley arrives in the evening. One of the diplomats met her five years ago in Vienna or in Berlin; and Lady Chiltern recalls that they once attended the same school ...

However, the newcomer is not configured for nostalgic dreams. With male decisiveness, she provokes an acquaintance with Sir Robert, mentioning a common acquaintance in Vienna - a certain Baron Arnheim. Hearing this name, Sir Robert winces, but imitates a polite interest.

Alien to soft-bodied sentimentality, she puts the cards on the table. Influential in political circles, Sir Robert is preparing to deliver a speech in parliament dedicated to the next "scam of the century" - the construction of the Argentine Canal, which threatens to turn into the same grand swindle as Panama. Meanwhile, she and the people behind her have invested considerable capital in this fraudulent action, and it is in their interests that it be supported by the official circles of London. Sir Robert, not believing his ears, refuses to be indignant, but when she casually mentions a certain letter at her disposal and signed by his name, reluctantly agrees.

The upcoming speech of Sir Robert becomes the subject of discussion between him and his attorney Gertrude. For a long time, despising Mrs. Chivley (who was once kicked out of school for theft), Lady Chiltern demands that her husband give written notice to the impudent blackmailer about her refusal to support the fraudulent project. Knowing that he is signing his own death sentence with his own hands, he yields.

Sir Robert makes the trustee of his far from impeccable past a long-time friend of Lord Goring, who is sympathetic, all-understanding, condescending and seriously involved in the younger sister of the baronet Mabel. Eighteen years ago, as Lord Radley’s secretary and possessing no capital other than a generic name, Robert informed the exchange speculator about the upcoming purchase of shares in the Suez Canal; he made a million, and allocated a substantial percentage to his accomplice, which laid the foundation for the property success of his current comrade minister. And this shameful secret from any minute can be made public and, worst of all, literally idolized by her husband Lady Chiltern.

And this is what happens: without catching Sir Robert, an enraged Mrs. Chivley throws a monstrous accusation into Gertrude's face, repeating his ultimatum. She is literally crushed: the heroic halo of her husband in her eyes fades. The returning Sir Robert does not deny anything, in turn, bitterly taking up arms against the eternal female idealism, prompting the weaker sex to create false idols for himself.

Bored alone with his butler, Lord Goring (“You see, Phipps, it’s unfashionable that others wear. And fashionable that you wear yourself”) receives a note from Lady Chiltern: “I believe. Want to see. I will come. Gertrude". He is thrilled; however, instead of a young woman, as usual inappropriately, his high-ranking father appears in the library of his luxurious apartment. The embodiment of British common sense, Lord Caversham reprimands his son for celibacy and idleness; Lord Goring asks the butler to immediately lead the expected lady to his office. The latter does appear soon; but the exemplary dandy does not know that, contrary to expectations, gave him a visit from Mr. Chivley.

Feeling sentimental weakness to him in the old days, the “business woman” (at one time they were even engaged, but the engagement was immediately upset) invites the long-time lover to start all over again. More than that: she is ready to sacrifice a letter of compromising Sir Robert for renewed affection. But true to his ideas of honor (and gentlemanly freedom), Lord Goring rejects her claims. Instead, he catches the guest with a longstanding vice: the night before at the reception, a brooch lost by someone caught his eye. She was dropped by Mrs. Chivley, but in the diamond snake, which can also be worn as a bracelet (which is not known to Mrs. Chivley herself), he recognized the thing he had gifted ten years ago to his high-ranking cousin and later stolen by someone. Now, fighting the blackmailer with her own weapons, he closes the bracelet on Mr. Chivley’s wrist, threatening to call the police. Fearing a revelation, she is forced to part with a testimony incriminating Sir Robert, but in retaliation she is stealing a letter from Gertrude Chiltern lying on the corner of the table. Powerless to destroy the baronet’s political career, she is determined to destroy his family well-being.

A few hours later, Lord Goring, who was visiting the Chiltern’s house, learns that the thunderous speech against the “Argentinean project” delivered by Sir Robert in Parliament brought him major political dividends. On behalf of the Prime Minister, Lord Caversham appears here, authorized to offer the Minister’s portfolio to a brilliant speaker. Soon he himself appears - with the ill-fated letter in his hands, which the secretary gave him. However, the fears of breathless Gertrude and Lord Goring are vain: Sir Robert saw in Gertrude's letter only moral support for his beloved wife ...

Flattered by the prime minister’s proposal, under the pressure of the same Gertrude, he first refuses, claiming that his political career is over. However, Lord Goring (happy at that moment with Mabel’s consent to tie the knot with him) finally succeeds in convincing the adamant maximalist that leaving the political field would be the end of his existence for his friend, who does not imagine himself outside the noisy public battles. After a little hesitation, she agrees - simultaneously admitting to her husband that the letter that came to him was actually addressed to Lord Goring. He easily forgives his wife a fleeting weakness of spirit.

The chivalrous duel of oncoming generosity ends with the prophecy of the elderly Lord Cavershem: “Chiltern <...> I congratulate you. And if England does not go to ashes and fall into the hands of the radicals, will you ever be the prime minister, ”