A young girl named Fanny Price comes to live with her wealthy uncle and aunt, Sir Thomas and Lady Bertram. Fanny's family is quite poor; her mother, unlike her sister Lady Bertram, married beneath her, and Fanny's father, a sailor, is disabled and drinks heavily. Fanny is abused by her other aunt, Mrs. Norris, a busybody who runs things at Mansfield Park, the Bertrams' estate. The Bertram daughters, Maria and Julia, are shallow, rather cruel girls, intent on marrying well and being fashionable. The elder son, Tom, is a roustabout and a drunk. Fanny finds solace only in the friendship of the younger son, Edmund, who is planning to be a clergyman. Fanny grows up shy and deferential, caught as she typically is between members of the Bertram family.
Sir Thomas leaves Mansfield Park for Antigua, where he owns plantations. In his absence, two new figures arrive at Mansfield: Henry and Mary Crawford, the brother and sister of the local minister's wife. Henry and Mary are attractive and cheerful, and they soon become indispensable members of the Mansfield circle. Henry flirts extensively with Maria, who is engaged to marry the boring but wealthy Rushworth. He also flirts with Julia when it suits his purposes. At first, Mary is interested in Tom, the older son and heir, but she soon realizes that he is boring and not really interested in her. She finds herself increasingly attracted to Edmund, although the prospect of marrying a clergyman does not appeal to her, and she is often cruel to him on this account. In the meantime, Fanny has innocently fallen in love with Edmund, although she does not even admit this to herself. Yates, a visiting friend of Tom's, proposes that the group should put on a play. His idea is eagerly received by all except for Edmund and Fanny, who are horrified at the idea of acting. The play goes on anyways, however; Maria and Henry, as well as Mary and Edmund (who has been prevailed upon to take a role to avoid bringing in an outsider to play it), get to play some rather racy scenes with one another. When one of the women cannot make a rehearsal, Fanny is pressured to take a role. She is almost forced to give in when Sir Thomas makes a sudden entrance, having arrived from Antigua.