The three traveling companions, Ralph, Henrietta and Isabel, venture to London together. Ralph stays at his own house in Winchester Square, while the others stay at Pratt's Hotel. Ralph finds himself alone, thinking of Isabel. He deems this an "idle pursuit" that will lead to nothing. He notes that she is "full of premises, conclusions, emotions… asked more questions than he could answer, and launched brave theories" (120).
Ralph takes the two women around London. Isabel feels a strange pain left by her experience with Lord Warburton at Gardencourt. She perceives her own act to have been necessary, but notes how gracelessly she acted. Nevertheless, she feels some odd pride in the matter, a "feeling of freedom" that she enjoys (121).
Ralph introduces the women to Mr. Bantling, one of his acquaintances. He is a jolly, stout man of about 40, who very much enjoys Henrietta's company. He recommends that she stay with his sister, Lady Pensil, if she wants to experience a house that is less dull than Gardencourt.
Mr. Bantling accompanies Henrietta back to the hotel when she needs to return alone for another engagement. Henrietta does not see why she needs accompaniment, wondering why anyone should see it improper that she go alone. Nevertheless Mr. Bantling accompanies her. When the two head off together, Ralph speculates that the two may go far as a couple, whereas Isabel does not think it will very far because the two do not understand each other. Ralph says: "There's no more usual basis of union than a mutual misunderstanding" (124-125).
Isabel declares that she would like to go back to the hotel and have dinner by herself. Ralph suggests that she wants to dine alone because she is in fact expecting a visitor, vaguely referencing her past. Isabel declares that there is none of her past in England. Ralph tells Isabel that he knows from Warburton of the proposal. He tells her that he does not want to argue with her though, but rather only hear about her sentiments on the matter. He considers it a remarkable act to have rejected Warburton, because he unites both the extrinsic and intrinsic advantages of marriage. Isabel suggests that Ralph wanted her to marry Warburton, to which he responds that he merely has a great interest in watching her. "I shall have the thrill of seeing what a young lady does who won't marry Lord Warburton," he tells her (129). He is glad to have seen her do something unexpected. Isabel tells him, "I don't want to begin life by marrying. There are other things a woman can do" (129).
Ralph claims that she wants to "drain the cup of experience" (129). She denies this. "I only want to see for myself," she says. He claims to be satisfied with her answers, concluding that she wants to throw herself into a world that interests her. She denies this. "I don't know what you're trying to fasten upon me," she complains (130).
Isabel returns to the hotel. She has no hidden motive for wanting to go alone. Caspar Goodwood though comes to visit her at her hotel unexpectedly, having been informed of her whereabouts through Henrietta Stackpole. Isabel tells him that her silence to his letter was "an intention" (132). Isabel is not very nice to him, telling him that he simply does not fit into life. Isabel asks him to at least banish her from his mind for two years, and then they will at least be on good terms again. Caspar asks what he will gain from this, and she responds that she cannot promise anything. Caspar predicts she will marry someone else. Isabel claims that she does not need the aid of a clever man to teach her how to live. Isabel lets him know that she has already refused a man of great fortune and position.
Isabel declares that her independence is what she values most, and Caspar claims that he would deprive her least of all of that; he would merely give her means to exercise that independence. Isabel tells him she would like to choose her own fate. Caspar exclaims, "One would think you were going to commit some atrocity!" Isabel says that she very well may, but at least she would be free to do so. Caspar leaves, to return in two years. Isabel drops to her knees and hides her face in her arms as he leaves.
Isabel is in an agitated state when Caspar Goodwood leaves, and she is very relieved when he is gone. She recognizes that her love of liberty is still very theoretic rather than actively lived, but she feels that she has at least finally done something. Henrietta returns to the hotel and is upset that Isabel has sent Caspar away. Henrietta asks if Isabel knows where she is going, to which Isabel responds, "I find it very pleasant not to know. A swift carriage, of a dark night, rattling with four horses over roads that one can't see--that's my idea of happiness" (143). Henrietta retorts that she sounds like a heroine of an "immoral novel."
Henrietta and Mr. Bantling go off to see Lady Pensil in Bedfordshire, while Isabel and Ralph return to Gardencourt. Mr. Touchett's health has taken a turn for the worse.
When Isabel returns home, she hears someone playing the piano. Isabel sees a lady who is well dressed and who plays Schubert remarkably well. Isabel compliments the lady at the piano for her playing. Mrs. Touchett arrives for teatime. The woman introduces herself as Madame Merle, an old friend of Mrs. Touchett's. She is actually an American from Brooklyn, but Isabel had mistakenly thought that she was French.
Madame Merle is described as having intelligent grey eyes and being very graceful. She looks like a woman of experience, who also is sympathetic. Isabel admires her very much.
Isabel asks Ralph about Madame Merle, and he declares her the cleverest woman he knows. He admits that he was once in love with her, when Monsieur Merle was still living. Ralph reports that she has no children.
Meanwhile, Mr. Touchett is very sick. He tells Ralph he is dying, and makes him promise to take care of his mother. Mr. Touchett asks Ralph if he has thought about marrying Isabel, and Ralph smiles at the thought. Ralph though believes he should not marry at all, since he is in an advanced state of pulmonary disorder. He also claims that he is not in love with Isabel. He merely is interested to see what she will do with herself. He admits though that he would like to "put a little wind in her sails" (158). Ralph suggests to his father that he leave Isabel half of Ralph's fortune to Isabel. Mr. Touchett expresses doubts about the rightness of this action. "You say Isabel wants to be free, and that her being rich will keep her from marrying for money. Do you think that she's a girl to do that?" Mr. Touchett asks Ralph (161). Ralph recognizes that Isabel has very little of mind for money, but she does not recognize yet how poor she is.
Mr. Touchett thinks the act immoral, making everything so easy for a person. Ralph believes that it depends upon the person, and that he will be facilitating the execution of noble impulses. At last Mr. Touchett expresses his fear that Isabel may fall prey to fortune hunters. Ralph admits that it may be a risk, but that it is a small risk.
Ralph's analysis of Isabel's motivations for rejecting Lord Warburton also assume a form similar to the thoughts expressed by Isabel in previous chapters. But, she notably denies them. She proves herself to be very contrarian in nature through these actions. She simply wants to elude the ideas that others have for her, to assert her own originality and independence. This then becomes the theme of her denial of Caspar Goodwood: she wants to set off on her own, to act freely. Caspar Goodwood though foreshadows that whatever action may come of this may seem an atrocity to others.
Isabel is notably brought to her knees upon Caspar's departure. She reacts physically and violently to his presence. There is some suggestion that she is repressing her own sexual lust in his presence: he is often described as very imposing in nature, like a force that she cannot resist. In the Victorian age in which Henry James was writing, sex was certainly not a theme that was discussed. However, sexual desire is certainly an important part of his novels, and its repression often leads characters into inexplicable actions. This is one theory as to why Isabel rejects Caspar Goodwood: she is too sexually repressed to accept her undeniable physical attraction to him. She instead wants to believe she has a higher ideal and value. But it could all be a vapid fiction invented to avoid the sordid reality of her sexuality. (This theme will become a stronger possibility in later chapters.)
In Chapter 18, Ralph acts beneficently by giving Isabel half of his own fortune, giving her the means to be independent. So far money has played a seemingly insignificant role in the plot of the story. It does not matter that Lord Warburton and Caspar Goodwood are rich and Isabel is poor: she has rejected them. It is clear that everyone around Isabel has money, but she does not seem to think herself inferior for her lack of it. However, her impracticality about her "idea" of greatness is also reflected in her lack of means to carry out any kind of "idea." How could she continue to live and travel without financial help? Ralph, in other words, is giving her a means to realize her idea in life. However, Mr. Touchett foreshadows that this beneficent act may be immoral. It may cause Isabel to fall prey to fortune hunters, and put her into a situation she is not prepared to deal with.