Ten-year-old Fanny Price is sent from her impoverished home in Portsmouth to live with the family at Mansfield Park. Lady Bertram is Fanny’s aunt and her four children – Tom, Edmund, Maria and Julia – are older than Fanny. All but Edmund mistreat her and her other aunt, Mrs Norris, wife of the clergyman at the Mansfield parsonage, makes herself particularly unpleasant.
When Fanny is fifteen, Aunt Norris is widowed and her visits to Mansfield Park increase, as does her mistreatment of Fanny. A year later, Sir Thomas leaves to deal with problems on his sugar plantation in Antigua, taking with him his spendthrift eldest son Tom. Mrs Norris, looking for a husband for Maria, finds the rich but weak-willed Mr Rushworth, whose proposal Maria accepts but only for his money.
Henry Crawford and his sister Mary arrive at the parsonage to stay with their half-sister, the wife of the new incumbent, Dr Grant. With their fashionable London ways, they enliven the great house. Edmund and Mary then start to show interest in one another.
On a visit to Mr Rushworth's estate, Henry flirts with both Maria and Julia. Maria believes Henry is in love with her and so treats Mr Rushworth dismissively, provoking his jealousy, while Julia struggles with jealousy and resentment towards her sister. Mary is disappointed to learn that Edmund will be a clergyman and tries to undermine his vocation.
After Tom returns to Mansfield Park ahead of his father, he encourages the young people to begin rehearsals for an amateur performance of Elizabeth Inchbald's play Lovers' Vows. Edmund objects, believing Sir Thomas would disapprove and feeling that the subject matter is inappropriate but, after much pressure, he agrees to take on the role of the lover of the character played by Mary. The play also provides further opportunity for Henry and Maria to flirt. When Sir Thomas arrives home unexpectedly, he is furious to find the play still in rehearsal and it is cancelled. Henry departs without explanation, and in reaction Maria goes ahead with marriage to Mr Rushworth. The couple then settle in London, taking Julia with them. Sir Thomas sees many improvements in Fanny and Mary Crawford initiates a closer relationship with her.
Fanny, led by Henry Crawford at her celebration ballWhen Henry returns to Mansfield Park, he decides to entertain himself by making Fanny fall in love with him. Fanny's brother William visits, and Sir Thomas holds what is effectively a coming-out ball for her. Although Mary dances with Edmund, she tells him it will be the last time, as she will never dance with a clergyman. Edmund drops his plan to propose and leaves the next day, as do Henry and William.
When Henry next returns, he announces to Mary his intention to marry Fanny. To assist his plan, he has used his family's naval connections to help William achieve promotion. However, when Henry proposes marriage, Fanny rejects him, disapproving of his past treatment of women. Sir Thomas is astonished by her continuing refusal, but she does not explain, afraid of compromising Maria.
To help Fanny appreciate Henry's offer, Sir Thomas sends her to visit her parents in Portsmouth, where she is taken aback by the contrast between their chaotic household and the harmonious environment at Mansfield. Henry visits, but although she still refuses him, she begins to appreciate his good features.
Later, Fanny learns that Henry and Maria have had an affair which is reported in the newspapers. Mr Rushworth sues Maria for divorce and the Bertram family is devastated. Tom meanwhile falls gravely ill as a result of a fall from his horse. Edmund takes Fanny back to Mansfield Park, where she is a healing influence. Sir Thomas realises that Fanny was right to reject Henry's proposal and now regards her as a daughter.
During a meeting with Mary Crawford, Edmund discovers that Mary's regret is only that Henry's adultery was discovered. Devastated, he breaks off the relationship and returns to Mansfield Park, where he confides in Fanny. Eventually the two marry and move to Mansfield parsonage after Dr Grant secures a post in Westminster. Meanwhile, those left at Mansfield Park have learned from their mistakes and life becomes pleasanter there.
