Emma Woodhouse is almost twenty-one, attractive, clever, wealthy and a bit spoiled. She lives at Hartfield, a substantial property in Highbury, Surrey and since her mother died young she runs the house. Her father is affectionate but obsessed with ill health and needs coddling. Her sister Isabella is married to Mr John Knightley and lives with their children in London. Her governess and friend, Anna Taylor, has recently married Mr Weston and gone to live at Randalls half a mile away.
Emma feels that she got Miss Taylor and Mr Weston together and hopes to develop her talent at matchmaking for other friends. As another 'good work' she takes Harriet Smith under her wing. Harriet is 17, blonde, pretty and not at all bright. She boards at the local school, and doesn't know her parents. Emma has a romantic notion that Harriet must be the illegitimate daughter of an aristocrat. She encourages Harriet to develop 'elegant' hobbies and ideas, and to set her sights above the farmer Robert Martin, with whose family Harriet spent a happy six weeks the previous summer.
Instead, Emma promotes Mr Elton, the vicar, as a more 'gallant' and 'gentlemanly' potential husband. She encourages them to flirt by drawing Harriet's picture and asking for Mr Elton's contributions to Harriet's riddle book. While she and Harriet are visiting the poor, Emma pretends to break a shoelace, in order to prolong their conversation with Mr Elton. When Robert Martin proposes, Emma manipulates Harriet into refusing him by pointing out his social inferiority and 'helping' to write the rejection letter.
Mr Knightley, Emma's brother-in-law, and a regular visitor at Hartfield, criticises Emma's behaviour and they quarrel. Christmas arrives, and John and Isabella visit Hartfield. There is a party at the Weston's. During the carriage ride home Mr Elton proposes to Emma and she gives a shocked refusal. Elton has assumed that Emma's flirtatious behaviour meant she wanted to marry him - he has no thought of marrying Harriet. Emma is miserable, particularly because her blunder has hurt Harriet, and promises herself not to match-make again.
Two significant visitors are anticipated in Highbury: Frank Churchill, Mr Weston's son by his first marriage; and Jane Fairfax, the granddaughter of Mrs Bates and niece of Miss Bates - poor but popular local gossips. Jane was adopted as a child by some family friends, and is well educated, but will soon have to start earning her living as a governess: a bleak prospect.
Mr Knightley and Emma argue over whether Frank should have paid a visit before. Emma argues that he couldn't, Mr Knightley argues that he just wouldn't - a good man can always find a way to do his duty. Meanwhile, Mr Elton returns from holiday engaged to Augusta Hawkins, a vulgar bore from Bristol.
Emma takes Harriet for a miserably short visit to the Martins at Abbey-Mill Farm. Frank Churchill finally arrives and gets on very well with Emma. She imagines that he must be falling in love with her, and that she might be a little in love with him. They both attend a dinner at the Coles, which Emma had originally planned to skip because the Coles are trades people and only 'moderately genteel'. Over dinner everyone is talking about Jane Fairfax, who has been gifted anonymously with a piano. Emma hints to Frank that the present might be from Jane's friend's husband, Mr Dixon, implying that Jane might have had an adulterous affair during her time at Weymouth.
Mrs Weston wonders if Mr Knightley might be in love with Jane Fairfax - a suggestion which annoys Emma.
Frank and Emma plan a ball at the Highbury Crown Inn, but this has to be cancelled as Frank is summoned back to Yorkshire by his bossy, rich aunt, on whose cash he depends.
The newly-wed Augusta Elton arrives in Highbury, determined to take society by storm and to patronise 'Knightley' (she rudely leaves out the Mr), Emma and everyone else. The long-awaited ball is held. Mr Knightley kindly helps Miss Bates and Jane Fairfax with his carriage (normally he rides horseback just like a farmer), and dances with Harriet when Mr Elton snubs her.
Some gypsies, who demand money while she is out walking with a friend - Frank Churchill rescues her, harass Harriet. When Harriet confesses that she has taken a fancy to a man from a higher social class, Emma assumes that she means Frank. Emma, who has gradually realised that she doesn't want Frank herself, is encouraging.
It is now June. At Hartfield, Frank Churchill accidentally lets on that he knows some gossip about the local doctor buying a carriage. Since nobody has told him this, it seems that he must be having a secret correspondence with somebody in Highbury - Mr Knightley shrewdly suspects Jane Fairfax.
Mrs Elton commands a strawberry-picking party to Donwell Abbey, Mr Knightley's estate. Mr Knightley and Harriet walk and talk together. Frank Churchill makes an unexpected appearance. Jane Fairfax, who is quiet and agitated, leaves the house abruptly to walk home.
Mrs Elton organises a second 'exploring party' to Box Hill. Everyone is bad-tempered, with each social group rubbing the others up the wrong way. Frank and Emma flirt and play word-games without much enjoyment. In the course of this Emma is tempted to be witty and rude to Miss Bates, who, Emma suggests, has an endless supply of dull conversation. Mr Knightley scolds Emma for her cruelty - and she cries all the way home.
Emma repents of her bad behaviour. She visits Mrs and Miss Bates by way of apology and tries to be kinder to Jane Fairfax, who has just heard news that she has got a job as a governess, and is ill.
Frank's aunt, Mrs Churchill, dies. Now that he is financially secure, he reveals that he has been secretly engaged to Jane Fairfax, whom he met at Weymouth, since the previous October. The mysterious piano was his gift. The concealment explains his oddly brash, and Jane's oddly nervous, behaviour. Mrs Weston is worried that Emma will be heartbroken by the news, but she explains that she isn't - the man she had fallen for was Mr Knightley.
This revelation brings on Emma's full self-awareness that she is, and has always been, in love with Mr Knightley. He is in London and she, miserably, believes him to return Harriet's affection. When he comes back to Hartfield they talk in the garden. Mr Knightley is delighted to discover that Emma has never been in love with Frank. Mr Knightley hints that he, too, would like to be married. Emma assumes that he means to Harriet, and almost stops him speaking, but her better nature persuades her to listen as a friend - and her charity is rewarded by the discovery that he loves her.
Mrs Weston has a baby girl. The only two things preventing perfect happiness are Emma?s guilt about Harriet, and Mr Woodhouse's horror of Emma leaving home to marry - a thing she had sworn not to do. The first problem is solved when Harriet becomes engaged to Robert Martin during a trip to London. Her parentage is revealed: it turns out that her father is in trade, and not an aristocrat as Emma once imagined. Emma and Mr Knightley coming to live at Hartfield solve the second problem. All three couples - Harriet and Robert; Emma and Mr Knightley; Frank and Jane - are happily united.