Strether, Maria, and Waymarsh spend three days in London. On the third evening, Strether and Maria have dinner before attending the theatre; Waymarsh has decided not to accompany them. At dinner, Strether compares Maria with Mrs. Newsome. Maria's dress is cut low around her shoulders and she wears a broad velvet band about her throat; he recalls Mrs. Newsome's rather austere attire in similar circumstances. Strether is also struck by the fact that, since the "grey middle desert" of his life when his wife and son died, he has never taken anyone to dinner before this evening.
The characters in the play they attend make Strether think of Chad Newsome, the young man who is the object of his embassy from Woollett. Maria guesses that Strether has in fact come on a mission to rescue "a young man a wicked woman has got hold of" and asks, "Are you quite sure she's very bad for him?" Strether characterizes the woman, whom he has yet to meet, as without doubt "base, venal, out of the streets" and Chad as an "obstinate" boy. He also reveals that he has undertaken his mission on behalf of Mrs. Newsome, Chad's mother, whom he describes as "delicate, sensitive, high strung." Mrs. Newsome is wealthy, he explains, and wants Chad to return to Woollett to manage the family business, "a great production, a great industry" engaged in the manufacture of a common domestic article, the exact nature of which Strether never reveals. He does reveal, however, that Mrs. Newsome pays for the publication of the Review, a magazine which he edits and which, he confesses, provides his "one presentable little scrap of identity" from among the "wreck of hopes and ambitions . . . disappointments and failures."
Returning to the subject of Strether's mission, Maria suggests that either of two quite distinct things may have happened to Chad as a result of his European involvements: "One is that he may have got brutalised. The other is that he may have got refined." Strether finds the latter possibility doubtful and contends that Chad needs to be "protected" from life. Maria correctly interprets this to mean that Chad is to be married off, and Strether admits that their intention is to marry Chad to Mamie Pocock (the sister of Jim Pocock, who is the husband of Sarah, Chad's sister). As they wait for a cab after the play, Maria asks Strether what he expects to gain from his mission, and he replies, "Nothing." "What do you stand to lose?" she asks, and in a burst of candor, Strether confesses, "Everything."
The comparisons Strether makes regarding Maria and Mrs. Newsome are revealing; for example, Strether at one point recalls that Mrs. Newsome, dressed for the opera in her black silk dress and lace, looked like Queen Elizabeth; he also observes that Maria looks like Mary Stuart. (In 1587, Mary Stuart, Queen of Scots, was executed by Queen Elizabeth for treason.) Strether and Mrs. Newsome have never enjoyed a romantic, candle-lit dinner such as this one. Strether now asks himself why not.
The "wicked woman" of Strether and Maria's conversation is Madame de Vionnet. The irony of Strether's attitude at this point will become evident when he later meets Madame de Vionnet.
Strether's allusion to "the very secret of the prison-house" is drawn from the Ghost's speech in the first act of Hamlet and refers to the mysteries of the spirit world.