Near the turn of the 19th century, Fanny Price (HANNAH TAYLOR GORDON), a young and poor girl from Portsmouth, is sent off to live with her far wealthier relatives in the lush countryside. Arriving at the sprawling estate known as Mansfield Park, Fanny is greeted by her two aunts, the condescending Mrs. Norris (SHEILA GISH) and her sister, the opium addicted Lady Bertram (LINDSAY DUNCAN). She's married to Sir Thomas Bertram (HAROLD PINTER), an older man who's made a fortune with his slave trade business, and he halfheartedly welcomes Fanny into his home.
Never their equal, Fanny (FRANCES O'CONNOR) grows up into a young woman there, developing a close bond with the family's youngest son, Edmund (JONNY LEE MILLER). The rest of his siblings, however, including sisters Julia (JUSTINE WADDELL) and Maria (VICTORIA HAMILTON) and older brother Tom (JAMES PUREFOY), see her as a mix of a destitute sister and servant girl.
Even so, Fanny has developed a certain confidence in herself and continues with her observational writing, continually sending letters back to her sister, Susan (SOPHIA MYLES), who still lives at home with their parents, (LINDSAY DUNCAN & HILTON McRAE). She gets more to write about when siblings Mary (EMBETH DAVIDTZ) and Henry Crawford (ALESSANDRO NIVOLA) arrive at Mansfield Park for an extended stay.
Attractive and charismatic, the two manage to stirs things up in the household, with both Julia and Maria interested in Henry, despite the latter being engaged and then married to Mr. Rushworth (HUGH BONNEVILLE). Yet the eligible bachelor is instead interested in Fanny, but she harbors secret romantic feelings for Edmund who in turn is interested in Mary.
As the respective family members and their guests jockey about for romantic pairings, things come to a head with Tom's refusal to follow in his father's footsteps and with Sir Thomas' insistence that Fanny marry Henry. With passions rising and facing an ultimatum, Fanny must decide how to play out her romantic future and what consequences her final choice will create.