When Catherine of Aragon fails to produce a male heir to the English throne, the Duke of Norfolk and his brother in law Thomas Boleyn scheme to install the latter's elder daughter Anne in the court of Henry VIII as the king's mistress and potential mother of his son, thereby furthering their own political ambitions. Their plan backfires when Henry, injured in a hunting accident indirectly precipitated by Anne, is nursed by her sister Mary and becomes smitten with her. With great reluctance, the recently married Mary and her husband William Carey agree to accept positions in the court, knowing full well what will be expected of her. Separated from her spouse, who is sent away on an assignment by the king, Mary finds herself falling in love with Henry.
Rebellious Anne secretly marries betrothed nobleman Henry Percy and confides in her brother George, who tells Mary about the elopement. Concerned that Anne will ruin her reputation by marrying a nobleman without the King's consent, she alerts her father and uncle of the union. They confront Anne, who argues that the marriage has been consummated and what is done before God cannot be undone, and she is exiled to France in disgrace.
The Boleyn family's fortunes seem to be secured when Mary becomes pregnant. When she nearly suffers a miscarriage, she is confined to bed for the remainder of her pregnancy, and Norfolk recalls Anne to England to keep Henry's attention from wandering to another rival, particularly Jane Seymour. Anne successfully embarks on a campaign to seduce Henry, revealing herself to be more sophisticated and accomplished than she was prior to her exile. By withholding her sexual favors, she ensures the king's continued interest, finally making him promise never to bed his wife or speak to her sister in exchange for her giving him hope of eventually possessing her. Anne exacts this promise just after Mary gives birth to the much-anticipated son, making Mary's triumph hollow.
The ambitious Anne encourages Henry to break from the Roman Catholic Church when Pope Clement VII refuses to annul his marriage to Catherine. Henry succumbs to Anne's demands, declares himself the Supreme Governor of the Church of England, and divorces his wife. The scandal of Anne's brief, secret marriage to Henry Percy threatens her forthcoming marriage to the king until Mary, out of loyalty to her family, returns to court and lies on Anne's behalf, assuring Henry her union with Percy never was consummated. Anne weds Henry and becomes Queen of England. The sisters reach a reconciliation and Mary stays by Anne's side at court.
Despite the birth of a healthy daughter, Elizabeth, Henry is unhappy with Anne's failure to deliver a son and legitimate male heir to the throne. After she miscarries their second child, a now desperate Anne asks her brother George to try to impregnate her. Although he ultimately refuses to grant her request, his neglected wife Jane witnesses enough of their encounter to become suspicious. Her testimony leads to the arrest, trial, and execution of both George and Anne. Mary returns to court to plead for her sister's life, but Henry refuses to intercede. He warns Mary never to come to court again, because her family's disgrace could result in danger to her as well. Mary fulfills her last promise to Anne and takes care of her infant daughter.
The closing captions reveal that perhaps the king should not have been concerned about his failure to produce a legitimate male heir, because, ironically, his daughter Elizabeth served her country well for forty-five years.