Henry seems to have improved greatly in Fanny's estimation, but any changes to his character must be viewed with caution. He is, after all, an actor, and a spoiled child who desires what he cannot have - in this case, the unattainable Miss Price. Based on his past actions, if Henry were to actually win Fanny's hand in marriage, he would tire of her quickly. Fanny, however, is beginning to waver: "she thought she was really good-tempered." When faced with the loss of the Mansfield lifestyle, Fanny's beliefs about love and marriage appear to weaken. Soon after, Fanny receives a long letter from Mary, in which she writes about Henry's visit to Portsmouth. Her remarks about Edmund seem like an afterthought: the primary result of his visit to London, she writes, was that her friends approved of his appearance. Edmund has not as yet proposed to Mary. Fanny is angered by the letter, and once again comes to view Mary as part of the superficial London crowd. However, she feels certain that Mary will bully Edmund into doing what she desires, and that after she has accomplished her intent, she will accept his proposal. She is disheartened by this development, but finds her improved friendship with Susan very rewarding. If she were to marry Henry, she imagines, he would not be averse to having Susan live with them.
A deeply distressed Fanny finally receives a letter from Edmund, who has returned from London. He writes to Fanny of his annoyance over Mary's enthrallment with her London friends, whom Edmund sees as very bad influences. He confides in Fanny his deep love for Mary and tells her that he could never think of marrying anyone else: "I cannot give her up, Fanny. She is the only woman in the world whom I could ever think of as a wife." Also, Edmund impresses upon Fanny his continuing hope that Fanny will marry Mary's brother, Henry, whom he has just seen in London. Maria and Julia, his sisters, remain in London, and he has been greatly enjoying their company. He tells Fanny how much everyone misses her at Mansfield. Lady Bertram speaks for her every hour, but Sir Thomas will not be able to come and get her until after Easter. Edmund tells Fanny that the Grants are going to Bath, and that he desperately wants her to come home. Lady Bertram is slightly angered that Edmund has informed Fanny about the Grants' trip to Bath. She has become a champion at writing long passages about nothing at all, and is annoyed that she has been deprived of the chance to deliver "real" news. However, she soon has real news of her own for Fanny: her son Tom, the heir to the estate, has become seriously ill in London, and Edmund has left to care for him. Tom continues to decline and is returned home, where he becomes even sicker. This event distracts the family from the issue of Fanny's return to Mansfield, and Fanny sinks into sadness.
Another letter from Mary Crawford - a desperate request for information - arrives, and angers Fanny considerably. Finally, she can see her friend's true character. Mary views Tom's possible death in a positive light because it would mean that Edmund would be the heir to the estate, and the sound of "Sir Edmund" is music to her ears. She also mentions that Henry is still head over heels in love with Fanny, and that he has been staying near Maria. Strangely, however, she says that Fanny should not be jealous. Fanny is disgusted by the letter, which presents Mary as a manipulator interested only in money. The idea that Edmund might marry this girl makes her feel upset and helpless.
To Fanny's great surprise, another mysterious letter arrives from Mary warning Fanny not to believe any gossip she might hear about Henry. By now, Fanny has become somewhat convinced that Henry harbors real affection for her. Her father, however, dispels this notion by bringing to her attention a newspaper article about a scandal in the Rushworth family: a "Mrs. R", it seems, has run off with a "Mr. C." Realizing that Maria Rushworth has run off with Henry Crawford, Fanny is deeply shocked, and her heart immediately goes out to her family at Mansfield. Soon after, another letter from Edmund follows, in which he states that he will pick Fanny up at Portsmouth in two days, and that Susan is invited to accompany her to Mansfield. Despite the tragedies, Fanny is overjoyed to be returning to what has become her true home: "she was, she felt, in the greatest danger of being exquisitely happy." The family now needs her very much, especially in light of the bad news that is still to come: Julia has eloped with Yates, and Maria and Henry are yet to be found.
A deeply saddened Edmund arrives to pick up Fanny and Susan. Although he is distraught, he cannot speak to Fanny in Susan's presence. Lady Bertram is delighted to see Fanny: "dear Fanny, now I shall be comfortable." Susan is warmly welcomed, although Mrs. Norris seems to be shell-shocked about the goings-on. Maria, after all, was her favorite, and she was responsible for making the match with Rushworth. She blames Fanny for everything-had Fanny married Henry Crawford like she should have done, none of this would have happened. Lady Bertram tells Fanny that Sir Thomas had received word from an old London friend about the flirtation between Maria and Mr. Crawford, and had been ready to leave for London when they heard of the couple's disappearance. Meanwhile, Tom continues to decline deeper into illness. The match that Sir Thomas looked forward to between Edmund and Mary has now evaporated. During this era, the sins of any one member of a family reflected upon the characters of all.
The crestfallen Edmund seems to be avoiding Fanny until one rainy Sunday evening, when he comes to her, heart in hand. Edmund, it seems, saw Mary right after her brother left with Maria. To his horror, Mary was only concerned with how she would be able to cover up the happenings and find a way for her brother and Maria to regain their standing in society. They must be married, she exclaimed, expressing no horror over their behavior. She was only angry that the two weren't more discreet. Mary, it seems, also blames Fanny for not marrying Henry so that all of this scandal could have been avoided. Finally, Edmund sees the darkness of Mary's character, and is free from her influence. Fanny can now tell Edmund of Mary's statement that she wished that Tom would die so that she would be able to marry a man with money and property. Edmund tells Fanny that he will never love again.
In time, things return to normal at Mansfield Park. Sir Thomas takes responsibility for having allowed Maria to marry Rushworth. Julia returns, begs forgiveness, and is welcomed back into the family along with her new husband, Yates. Tom recovers and becomes, like his father, much more serious. Edmund foregoes his vow never to love another woman, and begins to look at Fanny with a husband's eyes. Maria and Henry live together until the newly-divorced Maria realizes that he will never marry her and leaves him. Mrs. Norris goes to live with Maria, as neither one is wanted at Mansfield. The Grants cannot lift their heads in town after Henry's display of behavior, and leave the parsonage of Mansfield for Westminster, where they live with Mary. Fanny and Edmund marry, to everyone at Mansfield's great delight, and soon after move into the parsonage. The parsonage "grew as dear to [Fanny's] heart and as thoroughly perfect in her eyes [as Mansfield]." Susan takes over Fanny's position at Mansfield. William's naval career continues to progress, and Sir Thomas ultimately finds that helping the Price children has paid off handsomely in the pride that he feels over their successes.
The action speeds up as the novel comes to a close. Fanny's is once more vindicated. While everyone at Mansfield has misjudged what was happening right in front of their eyes, Fanny has remained steadfast in her beliefs. The whole family comes to realize how much they rely upon Fanny's integrity and good sense. Here, Austen reveals one of her most deeply-held beliefs: upward social mobility should be available to those who are worthy. The British social system, which casts the aristocracy as morally superior, should be re-examined. Indeed, quite often the members of the upper crust live immoral lives, while it is their lowly brethren who are made out of stronger moral fiber. For instance, Sir Thomas has been unable to see the true characters of his daughters, who from the beginning believe themselves to be superior to Fanny in every way. He leaves them in harm's way by handing them over to the ineffectual Lady Bertram and the miserly Mrs. Norris when he travels to Antigua. During this interval, they meet Henry Crawford and Mr. Yates, the men who are to be their undoing. More directly, Sir Thomas fails them by allowing Maria to marry a man she doesn't love solely for money and prestige, and by not ensuring that Julia receives proper attention in London.
The Bertram girls, who seem to have everything at their fingertips, act as foils for Fanny, who has nothing but a true heart - something that someone from any social rank is capable of possessing. Tom, the heir, is a ne'er-do-well, frolicking in London with friends and drinking too much, until he is taught a lesson by a severe bout of illness. Edmund has also been tempted and found wanting: his beliefs are quickly compromised by his desire for a woman intent on power and prestige. To Fanny's credit, however, she does not think enough of money to sacrifice her morals. The manipulative, money-grubbing Mary Crawford also acts as a foil for Fanny, who would rather be poor and isolated than surrender her values. In the end, Mary is revealed as what she truly is: a vile manipulator concerned only with appearances. Fanny, in contrast, is ultimately seen for what she is: a fair-minded, morally upright woman who loves Edmund deeply despite his faults.
In the final section of the novel, Austen once again highlights the discrepancy between town and country. All is well at Mansfield, the country, until evil arrives in the form of Mary and Henry Crawford, Mr. Yates, and Tom Bertram, all of whom hail from London. In the absence of Sir Thomas, the young people act immorally by deciding to put on a highly subversive play. Things become more subdued upon Sir Thomas's return, but Mary and Henry continue to wreak havoc on the country inhabitants. Tom lives in the evil city, where his misadventures soon make him seriously ill. He must live in the country for some time before he is returned to health and able to assume his duties as the new Sir Thomas. Mary Crawford seems to adapt to country ways during her stay at Mansfield, but almost immediately becomes contaminated upon her return to the town. In the country, Henry appears to truly be smitten with Fanny, but shortly upon returning to London he becomes infected by the city's loose morality, and takes up with the married Maria Rushworth. Maria and Julia are both contaminated by London, while the pure Fanny never sets foot in town.
Fanny's marriage to Edmund signifies Austen's firm belief in companionate - rather than arranged - marriage. Oddly, Sir Thomas does not see marriage in this light, despite his own marriage to Lady Bertram, who hailed from a position far down from his on the social ladder. No doubt Edmund's marriage to Mary, whose income would have provided him with a far more comfortable lifestyle, would have deeply pleased Sir Thomas. After all, his estate will go to his oldest son. Sir Thomas also overlooks his personal history by pushing his daughter Maria to marry Rushworth simply because he is the richest man in the country. Similarly, he urges Fanny to wed Henry Crawford, a man whom she despises, because doing so will ensure her a comfortable lifestyle. He even goes so far as to punish her by sending her back to Portsmouth when she fails to follow his directives. Despite the examples of those around them, Edmund and Fanny's deep love and committed sense of companionship win out in the end.