The narrator creates his own Muse of the "Love of Fame." He has been tempted by Fortune and Money to write this novel, which he hopes will achieve fame for posterity. He implores the assistance of genius, humanity, learning, and experience.
Jones and Partridge have never been to London before. They search for the house of the Irishman who brought Sophia to London. He has returned to Ireland. The following day Tom searches for Sophia, but he is turned away from the Irishman's door by the porter. Tom bribes the porter to lead him to Mrs. Fitzpatrick's doorstep. He arrives ten minutes after Sophia has left. Tom strikes the waiting woman with his civility and comeliness. She agrees to approach Mrs. Fitzpatrick with Tom's request to see Sophia. Mrs. Fitzpatrick, who suspects that Tom is one of Squire Western's party, sends a reply that Sophia has left. Jones believes that Sophia is there but is still offended over the Upton affair. That night, after Tom has kept vigil near the door all day, Mrs. Fitzpatrick deigns to meet with him. She thinks that he is Blifil. Her maid Abigail believes that the visitor is Jones, since Mrs. Honour has been "more communicative" than Sophia. Mrs. Fitzpatrick agrees with Abigail.
Mrs. Fitzpatrick plots to return Sophia to her father, in order to reinstate herself in the favor of Mrs. Western and Squire Western. Mrs. Fitzpatrick is also distantly related to Lady Bellaston, whom she for help in dissuading Sophia from pursuing Tom. Lady Bellaston receives her with a smile and asks if Tom is as handsome as she has been told by her dressing lady, Etoff. Mrs. Fitzpatrick says that he is, so that Lady Bellaston begins to think of him as "a kind of Miracle in Nature." She desires to see Tom.
Tom, having watched Mrs. Fitzpatrick's door all day, meets her an hour early. Lady Bellaston swoops in, curtseying to Tom. The women show Tom some attention until Mrs. Fitzpatrick's Irish friend arrives. The conversation now becomes too dainty for the narrator to describe to vulgar ears. Jones retires after entrusting Mrs. Fitzpatrick with his address. Lady Bellaston declares that Sophia can be in "no danger" from such a fellow.
Tom knocks at Mrs. Fitzpatrick's door five times the following day, but every time the maid says that she is not at home. Tom and Partridge lodge themselves at a house in Bondstreet. A young man is residing on the first floor. He is one of those privileged "Men of Wit and Pleasure" who spend their days and nights in coffee-shops. That night, Jones hears an uproar downstairs. He runs downstairs and saves a young man, who is being beaten by his footman. A young woman stands nearby, wringing her hands. This woman is in fact Nancy, the boarding-house landlady's daughter, and the young man is Nightingale, who lives on the first floor. Nightingale asks Tom to drink with him, and Nancy joins the men. Nightingale explains that his footman referred to a young lady in a manner that enraged him.
Nancy's mother and sister return from a play. Although Tom is feeling despondent, he puts forward a gracious and entertaining front. Nightingale, Nancy, and Nancy's mother are delighted with Tom and invite him to breakfast. He is similarly pleased with them—Nancy is a pretty girl, as is her mother, who is almost fifty. Jones admires Nightingale for his "Generosity and Humanity" in spite of his foppishness. The man professes complete disinterestedness in affairs of love.
Partridge tells Jones that Mrs. Fitzpatrick has left her house, and that he does not know where she has gone. Jones cannot conceal his disappointment at breakfast, where the conversation revolves around love. A maid arrives with a parcel for Tom—it holds a domino mask and a masquerade ticket. Nightingale declares that Tom has a female admirer. Nancy and her mother, Mrs. Miller, now agree with Nightingale, but Tom secretly thinks that Mrs. Fitzpatrick must have sent the billet since she is the only woman who knows his address. Nightingale offers to accompany Jones to the ball. He invites Nancy and Mrs. Miller to join them, but Mrs. Miller says such an event is too extravagant for women who have to earn their living. Nightingale, who likes Tom's company, invites him to dinner in a tavern—Tom, not wanting to admit he has no money, says that his dining clothes have not yet arrived. Tom is ravenous and Partridge urges him to use Sophia's bank bill. Tom absolutely refuses. Partridge cries and begs Tom to take him home to Somersetshire. Tom tells Partridge that Allworthy never wants to speak to him again.
Nightingale immediately walks off with a woman at the masquerade, and encourages Tom to do the same. Tom searches the place for Sophia, but neither sees nor hears a sign of her. A Lady in a Domino mask suddenly slaps him on his shoulder and leads him to a separate room. She tells him he should end the affair with Sophia. Tom maintains that his love is a selfless one—he wants only the best for Sophia. This adds to the Domino lady's affection for him. Jones's gallantry emerges as he realizes that he needs to win this woman's favor in order to get to Sophia. An old lady interrupts their conversation and begins to follow them around the room. Nightingale saves Tom by deflecting her. Jones offers to chaperone the Domino lady home. She says that she has to visit a friend, and that she hopes he will not follow her—which puts that very idea in his head. He follows the lady into a house and, since her friend is nowhere to be seen, she asks Jones what people would think of the two of them being alone in a house at that time of the night. Then she unmasks herself—it is Lady Bellaston. She will contrive an interview with Sophia for him if he promises then to quit all thoughts of her.
Jones sends Partridge to change a fifty-pound note that he received from Lady Bellaston. Jones and Nightingale wait for Mrs. Miller to return for dinner. She arrives two hours late. She says that she has been to visit her cousin, who is giving birth in a cold house with no fire. Mrs. Miller warns her daughters not to marry into such poverty. Tom takes Mrs. Miller aside and, with tears in his eyes, wants to give her the fifty pounds he received from Lady Bellaston. Mrs. Miller compares him to Mr. Allworthy and takes ten guineas from him for the family. At the table, Nightingale offers to give the family a guinea. Nancy turns pale. The narrator remarks that some people regard charity as voluntary, and some regard it as a duty.
Jones meets with Lady Bellaston many times, but she does not fulfill her promise of fixing an interview with Sophia for him. Indeed, she begins to balk whenever Sophia is even mentioned. Jones sends Partridge to try to discover Sophia's whereabouts from the servants. Jones still worries about how to deal with Squire Western, who will disinherit Sophia if she marries against his will. Lady Bellaston has set Tom up in a "State of Affluence." He feels burdened by his obligations to her for her financial support. One night he receives a letter from her saying that they cannot meet at their usual place. Then a second epistle arrives, telling Tom to meet her at her home at seven o'clock that night. The lady owner of the house in Hanover Place has refused to provide cover for Lady Bellaston and her male friends any longer. Lady Bellaston decides to send Sophia to the play to get her out of the way for her rendezvous with Tom.
Jones has just dressed to visit Lady Bellaston when Mrs. Miller invites him to take tea with her cousin, Mr. Anderson. Jones and the man recognize each other instantly—it is the man who tried to rob Jones on the highway. The man thanks Jones profusely for saving his family, calling him an "Angel from Heaven." Mrs. Miller says that Jones will meet a great reward one day for his generosity. Jones says that witnessing the man's happiness has been the greatest reward. Mr. Anderson almost tells Mrs. Miller about the robbery, but then decides against it.
Tom arrives early at Lady Bellaston's house and waits in the drawing room. She has been held up on the other side of town. Sophia leaves the play after the first act and returns to the house. Unaware that anyone else is in the drawing room, Sophia walks up to a mirror and contemplates her face. Then she notices Jones, who has frozen in a corner.
After a couple of mutual exclamations of surprise, Sophia asks Tom if he has any business at Lady Bellaston's house. Tom says he has brought her pocketbook for her. On his knees, he begs pardon from her for his misbehavior in Upton with Mrs. Waters. Sophia says she does not mind this as much as the fact that he has bandied her name about the countryside. He clears himself of this accusation by informing her that it was Partridge who misused her name. Tom mumbles a marriage proposal, but Sophia says that she cannot disobey her father. Jones thumps his breast and says that he will never ruin her. Sophia starts crying into Jones's bosom, and he kisses away her tears.
Sophia asks him how he came to be in Lady Bellaston's drawing room, at which point Lady Bellaston herself enters the room. Realizing that Tom has not admitted to Sophia that he knows her, Lady Bellaston pretends not to know Tom. Sophia pretends that Tom is simply some man who has delivered her pocketbook. Lady Bellaston thinks that Sophia must have secretly prearranged the meeting with Tom. Tom, feigning ignorance of Lady Bellaston, tells her that he was given her address by a lady at a masquerade. Tom begs that his honesty in delivering the pocketbook be rewarded by his being allowed to visit Sophia again. Lady Bellaston consents. On the stairs Jones passes Mrs. Honour and tells her his address.
Once Jones has departed from Lady Bellaston's house, the woman exclaims to Sophia how good-looking he is. Sophia says that she did not take much notice of him and that she found him rather ungentlemanly. Lady Bellaston agrees, and decides aloud that she will not admit him to visit. Lady Bellaston makes a snide comment about Tom's clothing. Sophia upbraids her for her cruelty and lets slip that the man is Tom Jones. She attempts to cover up her mistake. Lady Bellaston enjoys tormenting Sophia. Sophia cannot sleep from her guilt at lying.
With the powerful, ruthless Lady Bellaston at its helm, Book XIII ushers in the city scene with all its accessories: the extravagant masquerade, and the financial and sexual temptations of Lady Bellaston. Book XIII works to introduce the reader to Lady Bellaston who, at this stage, appears daunting but not malicious. It also introduces the important characters of Mrs. Miller and Nightingale, who are to become Jones's closest friends in London, and his most loyal supporters. These characters appreciate Jones's goodness, which is immediately apparent to them—Jones wins Mrs. Miller's eternal devotion by offering the fifty pounds he has received from Lady Bellaston to her beleaguered cousin. This scenario indicates that Jones consistently thinks of others, in spite of his own troubles.
Nightingale is a lovable city character—he and Mrs. Miller are London people who are able to act selflessly and show true concern for others. Lady Bellaston and Mrs. Fitzpatrick, on the other hand, act merely out of selfishness. For example, Mrs. Fitzpatrick, wishing to ingratiate herself with her aunt and uncle, is quite happy to connive against her cousin Sophia.
Interestingly, the narrator does not transcribe much of the dialogue between the "upper-class" characters—in Chapter IV he states that he will omit the conversation on account of its being "too dainty for Vulgar ears." The reader realizes, however, that the narrator simply thinks that it is too boring and uninteresting to relate.
The narrator increases the weight of the intrigue by showering the reader with a plethora of new names and characters. He calls Lady Bellaston's maid Abigail, the name he used for Mrs. Honour at Upton, and he calls Mr. Anderson's children Tom and Molly, a technique of recycling similar names that deepens the mystery. He also introduces gives his hero hints of the supernatural in the eyes of others—Lady Bellaston, before she has even met Tom, thinks of him as a "Miracle of Nature" and Mrs. Miller, knowing Tom well, calls him her "good Angel."