Anne plans to leave her sister Mary at Uppercross and go stay with Lady Russell for a while. She reasons this move may put her more in contact with Captain Wentworth, because Lady Russell's house is decidedly closer to Kellynch.
Captain Wentworth returns to visit Uppercross after not being seen for two days. He had gone to visit his friends, Captain and Mrs. Harville, in Lyme. He tells the Musgroves about Lyme, and they are all eager to see it. It is decided that Charles, Mary, Anne, Henrietta, Louisa, and Captain Wentworth will form a party to go visit Lyme. The following day, they arrive at Lyme, a seaside town, and are delighted by it.
Three new characters are introduced. Captain and Mrs. Harville are friends of Wentworth from the Navy who have a house in Lyme, and Captain Benwick is staying with them. The Harvilles are extremely hospitable people with excellent manners. Though they have very small quarters, they have developed great contrivances to make the best use of their space and Anne considers it a very happy home. Captain Benwick was known as "an excellent young man and an officer" but he has fallen into a deep depression since the death of his fiancee, Fanny Harville, Captain Harville's sister. Benwick has turned to poetry as solace for his sadness.
On one of their visits with the Harvilles, it falls to Anne to make conversation with Captain Benwick. Although he is initially shy, Benwick opens up to Anne and begins discussing poetry passionately. Anne recommends that he include more prose in his daily reading. He takes her suggestion warmly, and Anne feels that she has done a good thing by patiently helping a grieving man to open up once more.
The next morning, the party goes for an early morning stroll by the seashore before breakfast. While they are walking up the steps, a gentleman stops to let them pass and cannot help but look at Anne. It is clear that he finds her very attractive. Captain Wentworth notices the man admiring Anne, and turns to admire her himself.
The party goes back to the Inn to have breakfast and they find that the gentleman who admired Anne is also a guest at their hotel. They inquire as to his name and find out he is Mr. Elliot, a gentleman of large fortune. Mary assumes it must be their cousin and father's heir! She wishes that they could have been introduced before Mr. Elliot left, but Anne reminds her that such an introduction might not be proper; their father has not been on good terms with Mr. Elliot for quite some time.
The party all goes out for another walk and is joined by Captain Benwick and the Harvilles. Captain Benwick seeks Anne's company again, and Captain Harville mentions that Anne has done quite a good deed in getting Benwick talking again and bringing him out of his shell. They continue on their walk and come to a set of stairs. Louisa insists on being jumped down them by Captain Wentworth. She gets down safely but enjoys the sensation so much that she desires to do it again. But she jumps a second too soon and lands on the wall, unconscious. Mary and Henrietta become hysterical, but Anne remains calm. She directs Captain Benwick to run for a doctor and Captain Wentworth to carry her to the Inn. The Harvilles insist that Louisa be brought to their home, and there the doctor comes to examine her.
The doctor concludes that she has a severe head injury, but all is not hopeless; she will most likely have a long recovery. The Harvilles offer their home for Louisa for as long as she needs it. They decide that Captain Wentworth, Henrietta, and Mary should travel back to Uppercross to give the news to the Musgroves. Wentworth praises Anne's capability to care for Louisa. But Mary objects and will not hear of leaving her sister-in-law. She decides to stay in Lyme and sends Anne back in the carriage with Captain Wentworth. Mrs. Harville, who has nursing experience, will care for Anne.
On the ride home, Captain Wentworth expresses the guilt he feels for Louisa's fall. He asks Anne her opinion regarding the plan for breaking the news to the Musgroves. She feels grateful that he values her opinion. Captain Wentworth tells the Musgroves of Louisa's fall, drops Anne off at home, and returns as soon as possible to Lyme.
Chapter 12 signals a climax in the novel's narrative. Persuasion is a linear narrative that is organized chronologically. The original edition of this novel was published in two volumes, the first volume ending at the close of Chapter 12. Louisa's fall is the greatest dramatic occurrence which has happened so far. By inserting the fall here, Austen creates a cliffhanger and encourages her readers to buy the second volume of her novel. In these chapters, the reader is shown the negative effects of what can happen when one is too stubborn. Louisa would not be persuaded to keep from jumping off the wall. Her firmness of mind means serious injury for her and significant guilt for Captain Wentworth. He is encouraged to rethink his initial judgment of the benefit of a "strong character."