Catherine has been at Northanger Abbey for a month. She expresses concern at overstaying her welcome, but Eleanor assures her there is no problem, and Catherine is quite pleased to stay. General Tilney has to go on a business trip for several days, leaving Catherine, Eleanor and Henry to do as they please. Henry must go to Woodston for a few days. One night, the General suddenly returns and calls Eleanor to him. When Eleanor returns to Catherine, she is nearly in shock and, mortified, tells Catherine that the General has forgotten an engagement in Hereford, and the whole family must go there in two days' time. Therefore the General has arranged for Catherine to be taken home to her family in Fullerton the very next day, as early as seven in the morning. Herding Catherine out of the house so abruptly is a terribly insulting gesture, which accounts for Eleanor's embarrassment.
Early the next morning, the two women part. Eleanor gives Catherine some money for her journey, and Catherine assures Eleanor that she will write, despite the General and his offense. Catherine is greatly saddened that she cannot say good- bye to Henry, who is still in Woodston.
On the way home, Catherine tries to figure out what offence she could have caused the General. He could not have found out that she briefly suspected him of murder, so she has no idea what she did to offend him, especially after he was so nice to her. She returns to Fullerton where she is welcomed by her family. She explains what has happened, and they are confused, but quiet their anger because Catherine asks to. The next day, Catherine sulks around the house. Mrs. Morland has no idea what is upsetting her. She never imagines that her seventeen-year-old daughter, just back from her first trip, might have fallen for a man. Catherine and her mother visit Mrs. Allen, and Mrs. Morland keeps up a steady stream of advice to Catherine.
Two days later, Catherine is still sulking. Suddenly, Henry arrives in Fullerton. Henry tells Mrs. Morland that the reason for his arrival is to make sure that Catherine made it home all right. Henry suggests that he pay a visit to the Allens, and Catherine joins him. On the walk to the Allens' house, he proposes to her, and she accepts. He explains that his father's bad behavior was due to John Thorpe. In Bath, when John thought Catherine loved him, he told General Tilney that Catherine was from a very wealthy family. The General then ran into John much later on his trip away from Northanger Abbey. John was angry, because he had learned that Catherine did not love him, and he angrily told the General that the Morlands were almost poor. Angered, the General had sent Catherine away to show his contempt for someone so impoverished. When Henry returned to Woodston and found out what happened, he had a big argument with his father and announced his intention to propose to Catherine. The two parted angrily, and the next day Henry set out for Fullerton.
Henry asks the Morlands for Catherine's hand in marriage. They are surprised, but they quickly give their consent to the marriage. However, in order to be proper, they refuse to allow the marriage until the General has given his own consent. Henry and Catherine also want the General's consent, but they fear that it will be some time before he will break down and agree to the union. Fortunately, in a few months Eleanor becomes engaged and then married to a wealthy noble. This puts the General in a good mood, and when Eleanor and her husband ask the General to allow Henry's marriage, the General agrees—but only after doing some research and discovering that the Morlands are not at all as poor as John Thorpe had claimed they were. The General sends a letter to Mr. Morland giving his assent, and Henry and Catherine are married.
General Tilney and Catherine clash frequently over the course of the novel. Catherine almost always finds the General grumpy and disagreeable, even if he is not a killer. She also dislikes the way he treats his children. It is possible to argue that the climax of the novel occurs when the General sends Catherine away. There is a sense of finality as Catherine exchanges good-byes with Eleanor and leaves without saying goodbye to Henry. We might suspect that this sense of finality is false. The narrator confirms the falsity in Chapter XVI, saying: "The anxiety of Henry and Catherine can hardly extend, I fear, to the bosom of my readers, who will see in the tell-tale compression of the pages that we are all hastening together to perfect felicity").
If we read Catherine's dismissal as the climax of the novel, everything that takes place thereafter is falling action. Henry's proposal is quickly tendered to Catherine when he arrives in Fullerton, and we do not get to read the exchange between Catherine and Henry as they get engaged; the narrator sums up the transaction in a few lines. The tone of the last two chapters suggests that the marriage of Henry and Catherine is a foregone conclusion, a loose end that the author needs to tie up. The narrator makes the frank statement that Henry did not become attracted to Catherine until after he realized she was attracted to him, a circumstance "dreadfully derogatory of an heroine's dignity." In short, the marriage is not nearly as important as Catherine's personal progression. The marriage seems almost a happy ending tacked on to placate the reader. The true journey of the novel is Catherine's coming of age.