The narrator believes in the passion of love, and condemns those who dispel the idea simply because they cannot prove its existence. He explains the difference between love and lust, saying that the latter is more comparable to hunger than it is any other emotion. He also draws attention to a quality within some people whereby they have generous traits, and receive gratification by helping others.
Squire Western’s sister - Mrs. Western - is a woman who can read the actions of others to see what they hide. Unfortunately, she is blind to any qualities that are not disguised, and is thus baffled by such an innocent and honest character as Sophia's. Mrs. Western crows over her superior ability to read human nature, which she regards as far greater than any of the qualities men may hold. After watching Sophia a while, she reveals the girl's secret (as she sees it) to Squire Western: Sophia is in love with Blifil.
In an attempt to hide her feelings for Tom, Sophia publicly diverts all of her attentions to Blifil. This behavior is what misleads Mrs. Western. Meanwhile, Squire Western is excited by the prospect of the match (since it would increase his family's land holdings), and tells Allworthy of Sophia’s attraction to Blifil. Allworthy says that, if the young people truly like each other, then he is happy. Squire Western is disappointed by this attitude; he believes matches should be made by families, not the individuals involved.
The narrator then speculates on the nature of wisdom.
Blifil is described as a passionless individual, but he can see the attraction in Squire Western’s fortune. Allworthy is not convinced that Blifil truly loves Sophia, and as he himself married for love (and not property), he had hoped his nephew will do the same.
Mrs. Western tells Sophia that her love for Blifil has been discovered, and that her impending union with Blifil has been blessed by both Allworthy and her father. Sophia, horrified by the prospect of marrying someone she hates, explains that it is Tom she loves. Mrs. Western is incensed with this idea, since Tom is a bastard. She tells Sophia that the marriage plans have already been set in motion, and will happen regardless of her inclinations.
Sophia appeals to Mrs. Honour, her maid, saying she hates and despises Blifil. Honour says she saw Tom by the canal, and Sophia dashes to meet him there. Unfortunately, because she takes too long to choose which ribbon to wear, she misses him by a few moments.
Squire Western approaches his daughter with his plan for her to marry Blifil. Sophia realizes that her aunt was trying to help, but misread her signs of affection. Blifil arrives for a meeting with Sophia, and though it is extremely awkward - mainly due to his ridiculous compliments and her utter silence - he expresses contentment with it. He is happy with the idea of her fortune and, as he does not understand love, he is not jealous of Tom. He still believes Tom’s affections are with Molly Seagrim.
Sophia tells her father of her passionate dislike for Blifil. Squire Western vows to disinherit her if she refuses the match, and he strikes her across the face.
Tom finds Sophia bleeding on the ground after her father hit her. He had been sent by Squire Western to find her and to support Blifil’s suit with her. Sophia and Tom cling to each other in despair.
Squire Western had never suspected that Sophia could have any affection for Tom, as the circumstances of Tom’s birth make him entirely inappropriate for her. However, when Mrs. Western hears that Tom is currently with her, she reveals Sophia's secret to her brother and he charges after them. As the Squire approaches them embracing, Sophia sees him and faints into Tom's arms. Squire Western kicks Tom out of the house.
Squire Western visits Allworthy. He is angry, believing that Allworthy has brought Tom up to poach his daughter. Western says he wants Tom to be kept away from his house. He will lock Sophia up and will force her to marry Blifil.
Blifil then provides damning information about Tom. He reveals how Tom got drunk on the night of Allworthy's sickness, but does not explain it was from celebration, instead making it seem Tom did not care about the man's recovery. Blifil further reveals that he and Thwackum saw Tom in the woods with Molly, and that Tom attacked them. Blifil had deliberately withheld this information until it could do the most damage, though Allworthy believes Blifil withheld the information from loyalty to Tom.
That night at dinner, Allworthy questions Tom over what Blifil has said, claiming he will banish Tom from the house if he cannot explain his actions. Overcome with emotion, Tom is not able to defend himself, and so Allworthy turns Tom out, giving him a piece of paper containing five hundred pounds. He is so saddened that he does not realize how much money he was given, and gossips later speculated that he left with absolutely nothing, with some thinking he was banished totally naked.
Tom walks away from the house and decides to give up his love for Sophia rather than cause her any further undue stress. He writes her a farewell letter, explaining his decision. When he is looking for his sealing wax, Tom throws everything from his pockets, including the paper containing the money from Allworthy. When he later realizes he has lost the paper, he returns to the spot, where he meets up with Black George. George had found the money, but does not tell Tom. He in fact pretends to help Tom look for it.
Tom asks George to take his letter to Sophia, and George complies. Sophia receives the letter and sends a reply, which she had written before reading his letter. In hers, she promises him she will never marry any other person. Her response makes Tom regret telling her he renounced his affections for her. Tom is extremely moved by her letter.
Sophia’s aunt lectures her on marriage, and how, in polite society, marriage is merely a contract of investment. When she continues to resist all attempts at her compliance, Squire Western has her locked in her room. She discusses Tom’s letter with Mrs. Honour, deciding Tom could not really have loved her if he renounces his affections so quickly. Sophia sends Honour to bring money to Tom via Black George, whose conscience this time forces him not to steal the money.
Squire Western tells his sister that he has locked Sophia up. They argue, with Mrs. Western saying that he does not understand how women work. Claiming she can win Sophia's compliance through gentler means, she asks for control of Sophia. The squire agrees.
The nature of love becomes central to the narrative in this Book. The narrator condemns those who do not believe in love, and compares the search for love to the hunt for gold – saying that those who may not find it can still know it is there. He distinguishes between love and lust in a bid to explain the different emotions Tom has for Sophia and Molly. In his strength and perseverance towards Sophia, Tom is painted then as a positive figure.
Meanwhile, Fielding reveals an ugly side of society through his depiction of arranged marriages. Allworthy’s hope that Blifil loves Sophia seems to be a reference to Fielding’s own happy marriage and belief in love. And yet nobody else seems to think like he does. Squire Western and his sister think only of money, and even the prospective groom does not seem in his lack of passion a deterrent to marriage. So intense is Squire Western's greed that his strikes his beloved daughter and is blind to the extent of her professed unhappiness.
There are several characters who are presented cynically in this section, too. Blifil’s lack of emotion and manipulation of information for his own ends makes him further disliked by the audience, and presents him as a clear contrast to Tom. And Mrs. Western is an example of someone who can only see the bad in people; in this way, she is something of a foil to Allworthy, who is blinded by trust in the goodness of others. Mrs. Western represents the cynical and affected lady about town who reads the deception in others, but has no understanding of truth, which is why she misreads Sophia’s feelings for Tom and Blifil. Her assertion that women can read people better than men has a powerful edge, which is sadly tempered by her clear error of judgment in Sophia’s case. Meanwhile, Allworthy is driven to cruelty towards Tom precisely because he does not have a grounded appreciation for the baseness of humanity. When confronted with the possibility of betrayal, he is unable to survey the situation unemotionally, and banishes the clearly noble character, while believing the lies of the insidious character. In the same way that Mrs. Western does not know how to handle innocence, Allworthy does not know how to handle baseness.
The passionate refusal of Sophia to obey her father, and his violent response to her refusal, is reminiscent of Shakespeare’s Romeo and Juliet. The squire has been blind to the developing love between Sophia and Tom, despite the fact he has encouraged the young man to spend more and more time in his household. In this respect, a comparison can also be made with Shakespeare’s Othello, specifically to Brabantio’s shock at being told that Desdemona is in love with Othello. Neither father believes that their daughters are of the same species as their loved ones.
Town gossip concludes that Tom may have left Allworthy penniless and naked. The reader is reminded of the inaccuracy of local opinion, and the social desire to speculate and embellish on the affairs of others.
Finally, Black George provides another manifestation of Fielding's interest in the human capacity for both meanness and kindness. His robbery of Tom's money will be costly for Tom, yet it is countered by the man's support in facilitating communication between the lovers. At this time, it is help Tom needs far more than he needs money. Fielding's desire to show "human nature" in all its complexities continues to pay dividends through these rounded characters who can not be easily dismissed or lauded.