Emma Woodhouse is handsome, clever, and rich, mistress of her widowed father's house at Hartfield and the first lady of the village of Highbury. With little to distress her and a high opinion of her own judgment, she fills an easy life with the project of arranging other people's marriages, beginning with the match she credits herself for making between her former governess, Miss Taylor, and the amiable Mr. Weston.
Flush with that success, Emma takes up Harriet Smith, a pretty, pliable girl of unknown parentage, and sets out to raise her. She persuades Harriet to refuse Robert Martin, a worthy young farmer who loves her, and steers her instead toward the vicar, Mr. Elton, certain he is falling for Harriet. The plan collapses when Elton, who has been courting the wealthy Emma all along, proposes to Emma herself and is appalled at the suggestion that he meant the portionless Miss Smith.
Two newcomers complicate Highbury: the charming Frank Churchill, Mr. Weston's grown son, and the reserved, accomplished Jane Fairfax. Emma flatters herself that Frank admires her and amuses herself by half-imagining a romance and by suspecting Jane of a secret. She is wrong on every count. Frank has been secretly engaged to Jane the whole time, and has used his attentions to Emma as a screen, a deception that leaves several people hurt once it is known.
The novel's turning point comes not from a love plot but from a public unkindness. On an outing to Box Hill, bored and showing off, Emma makes a sharp joke at the expense of the poor, talkative Miss Bates. Mr. Knightley, the one person who has always told Emma her faults, takes her aside and tells her plainly that it was badly done, that Miss Bates is poor and sunk in the world and deserved her compassion. Emma is overcome with shame, and from that mortification her real reformation begins.
When Harriet, encouraged once too often, confides that she now hopes to marry Mr. Knightley, the shock makes Emma see her own heart at last: Knightley must marry no one but herself. She faces how much mischief her vanity has done, to Harriet most of all. Knightley, plainly and without speeches, declares his love; Harriet is reconciled to Robert Martin and marries him after all; Jane and Frank are restored to each other; and Emma, humbled and clear-sighted, marries the man who told her the truth.