D'Artagnan follows Milady and hears her tell the coachman to go to Saint-Germain, a neighborhood too distant for him to follow on foot. Therefore, he decides to visit Athos; he tells him about Milady, but Athos is not sympathetic. Athos is cynical about all love affairs; he sarcastically tells d'Artagnan, "Go have an adventure with Milady. I wish you success with all of my heart."
D'Artagnan finds Planchet, they borrow two horses from Treville, and ride to Saint-Germain. There, Planchet sees a man whom he recognizes: the servant to Count de Wardes — the same servant whom Planchet fought outside Calais. D'Artagnan sends Planchet to the servant to see if Planchet will be recognized, and if he isn't, to find out if the count survived. After talking with Planchet for awhile, the count's servant leaves, and suddenly Milady's maid appears. She gives Planchet a note intended for the servant of Count de Wardes. The maid says, "For your master." Planchet takes the piece of paper to d'Artagnan, and they discover that it is a love note: Milady is asking the count for a rendezvous.
Later, while he is following Milady's carriage, d'Artagnan overhears Milady in a heated argument with a man. Impulsively, d'Artagnan comes to her rescue, but is told by Milady that she is not in danger; she is only arguing with her brother-in-law. After she leaves, the two men agree to a duel, along with a free-for-all with three friends to be brought by each duelist. The gentleman introduces himself as Lord de Winter. D'Artagnan returns home and tells the three musketeers that he has committed them to a duel. All three are excited at the prospect.
Before the duel, the Englishmen are clearly concerned that they are titled members of society and perhaps should not be fighting with mere "commoners." Therefore, Athos takes one of them aside and tells him who he really is. He also tells him that because he now knows Athos's true identity, Athos will have to kill him — and he does so only moments into the duel. Meanwhile, Porthos wounds his opponent in the thigh, picks him up, and carries him to the carriage. Aramis traps his opponent momentarily before the Englishman manages to escape. D'Artagnan fights Lord de Winter with cool detachment until he is able to unarm him; then graciously, he spares his life. In appreciation, de Winter arranges to introduce d'Artagnan to Milady, his sister-in-law, Lady de Winter.
When the two men arrive, Milady seems momentarily unhappy to learn that d'Artagnan spared de Winter's life, but quickly recovers her composure. She becomes gracious to d'Artagnan and soon d'Artagnan becomes a daily visitor to Milady's house.
Meanwhile, Porthos goes to his dinner engagement with Madame Coquenard, posing as her cousin. Her miserly husband is there, and their dinner is the poorest excuse of a meal that Porthos, a fastidious gourmet, has ever tried to eat. In addition, he is served the most foul-tasting wine that can be imagined. After the meal, he discovers that Madame Coquenard is as miserly as her husband; she almost faints when she hears how much money Porthos needs to buy new musketeer equipment for himself. Nonetheless, she promises to get most of the equipment (a horse, a mule, and some other things) from business acquaintances, and she further promises Porthos some money. Disappointed, hungry, and morose, Porthos goes home.
Hourly, d'Artagnan is falling more in love with Milady. He is not even aware that the lady's exceptionally pretty maid, Kitty, takes every opportunity to rub against him. Finally one day, Kitty takes d'Artagnan aside and tells him that her mistress does not love him. D'Artagnan, being young and ardent, does not believe Kitty, so she takes him up to her private room, next to her mistress' chamber. There, she gives d'Artagnan a note that Milady has written to Count de Wardes. D'Artagnan reads the note, an open plea for the count to take advantage of Milady's love for him.
After reading the note, d'Artagnan pleads with Kitty to help him take revenge on Milady, but Kitty refuses; she says that in matters of love, it's "everyone for herself." Just then, d'Artagnan recalls Kitty's languishing glances, her flirtatious greetings in the antechamber, the corridor, and on the stairs, those touches of the hand every time she meets him, and her deep, warm sighs. D'Artagnan is shrewd enough to realize how advantageous it would be to have Kitty as a mistress; therefore, for the rest of the evening, he turns his attentions to her.
When Milady calls to Kitty, d'Artagnan hides in a closet where he can overhear their conversation. He learns that Milady knows that d'Artagnan has foiled her plots; she says that she detests him, that he is a simple country fool, and that she hates him most for not killing Lord de Winter, her brother-in-law. Had d'Artagnan killed de Winter, Milady would have inherited an extremely large fortune. D'Artagnan realizes that Milady is utterly corrupt, a monster.
Because d'Artagnan has won Kitty's love, she is eager to please him, so she brings him another letter that Milady has written to Count de Wardes. D'Artagnan forges an answer, setting up a rendezvous for 11 p.m., and signs the count's name. Kitty fears the consequences, and she doesn't want to deliver the letter, but she is finally persuaded to especially after he reminds her what vengeance Milady would take against her if she ever found out about Kitty's betrayals.
When Athos tells d'Artagnan to go and amuse himself with Milady, little does Athos realize that he is telling d'Artagnan to amuse himself with the woman whom he once married — the woman whom he believes he murdered. This coincidence is, of course, one of the romantic ironies of this loose and seemingly rambling novel, but a novel which is nevertheless well-plotted. One would have thought that d'Artagnan would have recognized the name "Lord de Winter" since he had heard from Buckingham that it was "Lady de Winter" who cut off the diamond tags — but Dumas explains this puzzling detail by having d'Artagnan admit that de Winter's English name is so strange-sounding that he can't even pronounce it. Ultimately, all of these unlikely coincidences — that is, the accidental sighting in the church, the inadvertent interception of Milady's note to Count de Wardes, the duel with Milady's brother-in-law, and d'Artagnan's sparing his life — prepare us for the actual introduction of d'Artagnan to the beautiful Lady de Winter herself, the infamous Milady.
Chapter 31 presents another exciting duel scene, the type of scene that makes this novel a favorite of Hollywood filmmakers. Here, it is worth noting that the only Englishman killed is Athos's opponent; Athos, remember, confided his real name and social status to the Englishman. Athos's secret is so personal at this point in the novel that it is necessary that Athos kill the Englishman to make sure that his secret will not be revealed. Thus, for the present, Athos's real identity continues to be a secret, and his origins and background become even more intriguing.
Chapter 32 presents an entertaining interlude. It is an established comic device to pit an extreme miser (Madame Coquenard) against an extreme libertine and spendthrift (Porthos). We have continually seen that Porthos puts great emphasis on fine and delicate foods prepared to perfection. In earlier chapters, Porthos was the one who suggested spending money on good meals. Earlier too, he sold his beautiful English horse so that he could enjoy an elegant repast. Therefore, when we now see the finicky Porthos being subjected to watery soup, the wing of a scrawny chicken, inedible green beans, undrinkable wine, and a dessert that clogs the throat — all for the sake of getting Madame Coquenard to provide new musketeer equipment. This is an extremely comic situation from an author who is not particularly known for his comic touch. Dumas even satirically compares Madame Coquenard to Moliere's famous character Harpagon in The Miser, but points out that Madame Coquenard lived many years before Moliere created his now-archetypal skinflint.
In Chapter 33, Dumas begins building suspense for one of the novel's most significant intrigues. We know that d'Artagnan has a great deal of pride and ambition, so it is not surprising that he realizes that Kitty is an exceptionally pretty mistress who can satisfy his immediate needs and whom he can use to revenge himself on Milady. This reasoning is prudent because without Kitty's help, d'Artagnan could never effect his long-range plans. He desperately lusts for Milady — even though he knows of her hatred for him — and yet, at the same time, he is desperate for revenge. He knows what a monster Milady is, but he cannot rid himself of his passionate desire to possess her: "He knew her to be treacherous in matters of more importance, and he had no respect for her, yet he felt an uncontrollable passion for this woman boiling in his veins — passion drunk with contempt but passion and desire nevertheless." Throughout d'Artagnan's relationship with Milady, we should be aware of Dumas's use of the modern-day love/hate dichotomy.