Anne Elliot is the overlooked middle daughter of the vain Sir Walter, a spendthrift baronet who is all too conscious of his good looks and rank. Anne's mother, a loving, intelligent woman, is long dead. Anne's older sister, Elizabeth, takes after her father, and her younger sister, Mary, is a nervous, attention-seeking fretful woman who is married to Charles Musgrove of nearby Uppercross Hall, the heir to a rustic but respected local squire. None of her family can provide much companionship for the refined, sensitive Anne, who is still unmarried at 27 and seems destined for spinsterhood. Nearly seven years after breaking her engagement and subsequently turning down a proposal from Charles Musgrove, who went on to marry her sister, she has still not forgotten Frederick Wentworth.
Wentworth reenters Anne's life when Sir Walter is forced by his own financial irresponsibility to rent out Kellynch Hall, the family estate. He and Elizabeth move to pricey rental lodgings in the fashionable resort of Bath, while Anne remains behind in Uppercross with her younger sister's family. Kellynch's tenants turn out to be none other than Wentworth's sister, Sophia, and her husband, the recently retired Admiral Croft. Wentworth's successes in the Napoleonic Wars have won him promotions and wealth amounting to about £25,000 (around £2.5 million in today's money) from prize money awarded for capturing enemy vessels, and he is now an eminently eligible bachelor. The Musgroves, including Mary, Charles, and Charles's younger sisters, Henrietta and Louisa, are happy to welcome the Crofts and Wentworth. He is deliberately cool and formal with Anne, whom he describes as altered almost beyond recognition, but extremely friendly and attentive with the Musgrove girls, who both respond in kind. Although Henrietta is nominally engaged to her clergyman cousin Charles Hayter, nothing is official, and both the Crofts and Musgroves, who know nothing of Anne and Frederick's previous relationship, enjoy speculating about which sister Wentworth might marry. All this is hard on Anne, who has spent the last several years bitterly regretting that she was ever persuaded to reject him and realises that he still holds her refusal against her. To avoid watching him keep company with the Musgrove sisters, particularly Louisa, whom he seems to prefer, she does her best to stay out of his way. When they do meet, his conspicuous indifference nearly breaks her heart.
The sad slow pace of Anne's life suddenly picks up when the younger adult members of the Uppercross family decide to accompany Captain Wentworth on a visit to one of his brother officers, Captain Harville, in the coastal town of Lyme Regis. There Anne meets yet a third officer, Captain James Benwick, a passionate admirer of the Romantic poets, who is in mourning for the death of his fiancée, Captain Harville's sister, and appreciates Anne's sympathy and understanding. The new location, new acquaintances, and fresh ocean air all agree with Anne, who begins to regain some of the life and sparkle that Captain Wentworth remembered, and she attracts the attention of another gentleman, who turns out to be the Elliots' long-estranged cousin, her father's heir, William Elliot. Louisa Musgrove sustains a serious concussion in a fall brought about by her own impetuous behaviour. Anne coolly administers first aid and summons assistance. Wentworth is both confused and impressed, and begins to re-examine his feelings about Anne.
Following this near-tragedy, Anne relocates to Bath to be with her father and sister, while Louisa stays in Lyme to recover her health at the Harvilles. In Bath Anne finds that her father and sister are as shallow as ever, obsessed with rank and wealth, and flattered by the attentions of William Elliot, recently widowed, who has now successfully reconciled with his uncle, Sir Walter. Elizabeth assumes that he wishes to court her while Lady Russell more correctly suspects that he admires Anne. However, although Anne likes William Elliot and enjoys his company, she finds his character disturbingly opaque, while admitting to herself that his admiration has done a great deal to lift her spirits.
Admiral Croft and his wife arrive in Bath, and soon afterward comes the news that Louisa Musgrove is indeed engaged—but not to Captain Wentworth. The lucky man is Captain Benwick, who had continued living with the Harvilles during Louisa's convalescence there. Wentworth also comes to Bath, where he is not pleased to see Mr. Elliot courting Anne, and he and Anne begin to tentatively renew their acquaintance. Anne also takes the opportunity to reunite with an old school friend, Mrs. Smith, a once prosperous matron who is now a widow living in Bath in straitened circumstances. Through her she discovers that behind his charming veneer, Mr. Elliot is a cold, calculating opportunist who had led Mrs. Smith's late husband into crippling debt. Although Mrs. Smith believes that he is genuinely attracted to Anne, it appears that his real aim in making up to the Elliots has been to keep an eye on the ingratiating Mrs. Clay, whom he worries that Sir Walter may take it into his head to marry. A new marriage might mean a baby boy, and the end of Mr. Elliott's inheritance. Although Anne is shocked and dismayed by this news, it helps to confirm her belief that she is the best judge of what will constitute her own happiness.
Ultimately, the Musgroves visit Bath to purchase wedding clothes for their sisters Louisa and Henrietta (who is now officially engaged to Charles Hayter). Captain Wentworth and his friend Captain Harville encounter them and Anne at the Musgroves' Bath hotel, where Wentworth overhears Anne and Harville conversing about the relative faithfulness of men and women in love. Deeply moved by what Anne has to say about women never giving up their feelings of love even when all hope is lost, Wentworth writes her a note declaring his feelings for her. Anne and Wentworth reconcile, affirm their love for each other, and renew their engagement. The story ends less well for Anne's father and sister. They are both jilted by Mr. Elliot, who succeeds in persuading Mrs. Clay to become his mistress. Lady Russell admits she was wrong about Wentworth; she and Anne remain friends; and Wentworth helps Mrs. Smith recover some of her lost assets. Nothing remains to blight Anne's happiness—except the prospect of another war.