Lambert Strether is engaged to marry Mrs. Newsome, a widow. Mrs. Newsome has a son, Chadwick, called Chad, whom she wants to return home from Paris and take over the family business in Woollett, Massachusetts. She is especially concerned for his future after she hears that he is seriously involved with a Frenchwoman. In her anxiety, she asks Strether to go to Paris and persuade her son to return to the respectable life she planned for him. Strether does not look forward to his task, for Chad ignored all of his mother’s written requests to return home. Strether also does not know what hold Chad’s mistress might have over him or what sort of woman she might be. He strongly suspects that she is a young girl of unsavory reputation. Strether realizes, however, that his hopes of marrying Mrs. Newsome depend upon his success in bringing Chad back to America, where his mother can see him married to Mamie Pocock.

Leaving his ship at Liverpool, Strether journeys across England to London. On the way he meets Miss Gostrey, a young woman who is acquainted with some of Strether’s American friends, and she promises to aid Strether in getting acquainted with Europe before he leaves for home again. Strether meets another old friend, Mr. Waymarsh, an American lawyer living in England, whom he asks to go with him to Paris. A few days after arriving in Paris, Strether goes to Chad’s house. The young man is not in Paris, and he temporarily gave the house over to a friend, Mr. Bilham. Through Bilham, Strether gets in touch with Chad at Cannes. Strether is surprised to learn of his whereabouts, for he knows that Chad would not dare to take an ordinary mistress to such a fashionable resort.

About a week later, Strether, Miss Gostrey, and Waymarsh go to the theater. Between the acts of the play, the door of their box opens and Chad enters. He is much changed from the adolescent college boy Strether remembers. He is slightly gray, although only twenty-eight years old. Strether and Chad are pleased to see each other. Over coffee after the theater, the older man tells Chad why he came to Europe. Chad answers that all he asks is an opportunity to be convinced that he should return. A few days later, Chad takes Strether and his friends to a tea where they meet Mme and Mlle de Vionnet. The former, who married a French count, turns out to be an old school friend of Miss Gostrey. Strether is at a loss to tell whether Chad is in love with the comtesse or with her daughter Jeanne. Since the older woman is only a few years the senior of the young man and as beautiful as her daughter, either is possibly the object of his affections. As the days slip by, it becomes apparent to Strether that he himself wants to stay in Paris. The French city and its life are much calmer and more beautiful than the provincial existence he knew in Woollett, and he begins to understand why Chad is unwilling to go back to his mother and the Newsome mills.

Strether learns that Chad is in love with Mme de Vionnet, rather than with her daughter. The comtesse was separated from her husband for many years, but their position and religion make divorce impossible. Strether, who is often in the company of the Frenchwoman, soon falls under her charm. Miss Gostrey, who knew Mme de Vionnet for many years, has only praise for her and questions Strether as to the advisability of removing Chad from the woman’s continued influence. One morning Chad announces to Strether that he is ready to return immediately to America. The young man is puzzled when Strether replies that he is not sure it is wise for either of them to return and that it would be wiser for them both to reconsider whether they would not be better off in Paris than in New England.

When Mrs. Newsome, back in America, receives word of that decision on the part of her ambassador, she immediately sends the Pococks, her daughter and son-in-law, to Paris along with Mamie Pocock, the girl she hopes her son will marry. They are to bring back both Strether and her son. Mrs. Newsome’s daughter and her relatives do not come to Paris with an obvious ill will. Their attitude seems to be that Chad and Strether have somehow drifted astray, and it is their duty to set them right. At least that is the attitude of Mrs. Pocock. Her husband, however, is not at all interested in having Chad return, for in the young man’s absence, Mr. Pocock controls the Newsome mills. Mr. Pocock further sees that his visit was probably the last opportunity he will have for a spirited time in the European city, and so he is quite willing to spend his holiday going to theaters and cafés. His younger sister, Mamie, seems to take little interest in the recall of her supposed fiancé, for she is interested in Chad’s friend, Mr. Bilham.

The more Strether sees of Mme de Vionnet after the arrival of the Pococks, the more he is convinced that the Frenchwoman is both noble and sincere in her attempts to make friends with her lover’s family. Mrs. Pocock finds it difficult to reconcile Mme de Vionnet’s aristocratic background with the fact that she is Chad’s mistress. After several weeks of hints and genteel pleading, the Pococks and Mamie go to Switzerland, leaving Chad to make a decision whether to return to America. As for Strether, Mrs. Newsome advises that he be left alone to make his own decision, for the widow wants to avoid the appearance of having lost her dignity or her sense of propriety.

While the Pococks are gone, Strether and Chad discuss the course they should follow. Chad is uncertain of his attitude toward Mamie Pocock. Strether assures him that the girl is already happy with her new love, Bilham, who tells Strether that he intends to marry the American girl. His advice, contrary to what he thought when he sailed from America, is that Chad should remain in France with the comtesse, despite the fact that the young man cannot marry her and will, by remaining in Europe, lose the opportunity to make himself an extremely rich man. Chad decides to take his older friend’s counsel.

Waymarsh, who promised his help in persuading Chad to return to America, is outraged at Strether’s changed attitude. Miss Gostrey, however, remains loyal, for she fell deeply in love with Strether during their time together in Paris. Strether, however, realizing her feelings, tells her that he has to go back to America alone. His object in Europe was to return Chad to his mother. Because he fails in that mission and will never marry Mrs. Newsome, he cannot justify to himself marrying another woman whom he meets on a journey financed by the woman he at one time intended to marry. Only Mme de Vionnet, he believes, can truly appreciate the irony of his position.