The plot of the novel begins seven years after the broken engagement of Anne Elliot to then Commander Frederick Wentworth. Anne Elliot, then 19 years old, fell in love and accepted a proposal of marriage from the handsome young naval officer. He was clever, confident, ambitious, and employed, but not yet wealthy and with no particular family connections to recommend him. Sir Walter, her father and her older sister Elizabeth were not pleased with her choice, maintaining that he was no match for an Elliot of Kellynch Hall, the family estate. Lady Russell, acting in place of Anne's late mother, persuaded her to break the engagement, for she felt it was an imprudent match for one so young. They are the only ones who know about this short engagement, as younger sister Mary was away at school.
The Elliot family is now in financial trouble. Kellynch Hall will be let, and the family will settle in Bath until finances improve. Baronet Sir Walter, the socially-conscious father and daughter Elizabeth look forward to the move. Anne is less sure she will enjoy Bath. Mary is married to Charles Musgrove of nearby Uppercross Hall, the heir to a respected local squire. Anne visits Mary and her family, where she is well-loved. The end of the war puts sailors back on shore, including the tenants of Kellynch Hall, Admiral Croft and his wife Sophia, who is the sister of Frederick Wentworth, now a wealthy naval captain. Frederick visits his sister and meets the Uppercross family, including Anne.
The Musgroves, including Mary, Charles, and Charles's sisters, Henrietta and Louisa, welcome the Crofts and Wentworth. He tells all he is ready to marry. Henrietta is engaged to her clergyman cousin Charles Hayter, who is away for the first few days that Wentworth joins their social circle. Both the Crofts and Musgroves enjoy speculating about which sister Wentworth might marry. Once Hayter returns, Henrietta turns her affections to him again. Anne still loves Wentworth, so each meeting with him requires preparation for her own strong emotions. She overhears a conversation where Louisa tells Wentworth that Charles first proposed to Anne, who turned him down. This is startling news to him.
Anne and the young adults of the Uppercross family accompany Captain Wentworth on a visit to two of his fellow officers, Captains Harville and James Benwick, in the coastal town of Lyme Regis. Benwick is in mourning for the death of his fianc e, Captain Harville's sister, and he appreciates Anne's sympathy and understanding. He admires the Romantic poets, as does Anne. Anne attracts the attention of a gentleman passing through Lyme, who proves to be William Elliot, her cousin and the heir to Kellynch, who broke ties with Sir Walter years earlier. The last morning of the visit, Louisa sustains a serious concussion in a fall brought about by her impetuous behaviour with Wentworth. Anne coolly organizes the others to summon assistance. Wentworth is impressed with Anne, while feeling guilty about his actions with Louisa. He re-examines his feelings about Anne.
Following this accident, Anne joins her father and sister in Bath with Lady Russell, while Louisa and her parents stay at the Harvilles in Lyme. Wentworth visits his older brother in Shropshire. Anne finds that her father and sister are flattered by the attentions of William Elliot, recently widowed, who has now reconciled with Sir Walter. Elizabeth assumes that he wishes to court her. Although Anne likes William Elliot and enjoys his manners, she finds his character opaque.
Admiral Croft and his wife arrive in Bath with the news that Louisa is engaged to Captain Benwick. Wentworth comes to Bath, where his jealousy is piqued by seeing Mr Elliot courting Anne. He and Anne renew their acquaintance. Anne visits an old school friend, Mrs Smith, who is now a widow living in Bath in straitened circumstances. From her she discovers that beneath his charming veneer, Mr Elliot is a cold, calculating opportunist who had led Mrs Smith's late husband into debt. As executor to her husband's will, he takes no actions to improve her situation. Although Mrs Smith believes that he is genuinely attracted to Anne, she feels that his first aim is preventing Mrs Clay from marrying Sir Walter. A new marriage might mean a new son, displacing him.
The Musgroves visit Bath to purchase wedding clothes for Louisa and Henrietta, both soon to marry. Captains Wentworth and Harville encounter them and Anne at the Musgroves' hotel in Bath, 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 not giving up their feelings of love even when all hope is lost, Wentworth writes her a note declaring his feelings for her. Outside the hotel, Anne and Wentworth reconcile, affirm their love for each other, and renew their engagement. William Elliot leaves Bath with Mrs Clay, whose charming ways may yet attract him. Lady Russell admits she was wrong about Wentworth; she and Anne remain friends. Once Anne and Frederick marry, he helps Mrs Smith recover her lost assets. Anne settles into life as the wife of a Navy captain, he who is to be called away when his country needs him.
Output: How old was Elizabeth's sister when she agreed to marry Wentworth?