When Catherine of Aragon is blamed for England's failure to produce a male heir, Thomas Howard, the Duke of Norfolk and his brother in law Thomas Boleyn plan to install Thomas's daughter Anne Boleyn in the court of Henry VIII of England. Howard and Boleyn hope Anne will become the King's mistress and potential mother of his son, thereby furthering their own political ambitions, much to the disgust of Thomas's wife and the duke's sister, Lady Elizabeth Boleyn, Countess of Wiltshire and Ormond. Although Anne initially refuses because she knows being a mistress can damage her reputation, she agrees to please her father and uncle. Anne's younger sister, Mary, marries William Carey, even though he had asked for Anne's hand. Her father thought that Anne could do better than William Carey and thus offered Mary as a substitute.
While visiting the Boleyn estate, Henry is injured in a hunting accident, indirectly caused by Anne, and is nursed by Mary. While in her care, Henry becomes smitten with her and invites her to court. With great reluctance, Mary and William agree, knowing what will be expected of her. Mary and Anne become ladies-in-waiting to Queen Catherine and Henry sends William away on an assignment for the royal court. Separated from her husband, Mary finds herself falling in love with Henry.
Rebellious Anne secretly marries the nobleman Henry Percy, who was engaged to Mary Talbot. Anne confides in her brother George, who is overjoyed and tells Mary about the secret marriage. Fearing Anne will ruin her reputation by marrying without the king's consent, Mary alerts her father and uncle about the secret elopement. The men confront Anne, who argues that what has been done before God can't be undone and that the marriage has been consummated. Despite this, the marriage is annulled and she is exiled to France in disgrace. Anne plans for revenge due to her belief that Mary exiled her to increase her own status.
Despite the scandal, the family's fortunes seem secure when Mary becomes pregnant. However, Elizabeth Boleyn warns Thomas and Norfolk that the king's favour can be taken away as easily as it is given, often with disastrous consequences. Despite her warnings, the men ignore her. Thomas Boleyn becomes Earl of Wiltshire and George becomes Viscount Rochford. They receive a number of new grants and estates, so their debts are paid and Henry arranges for George to marry Jane Parker, despite George wanting nothing to do with her.
When Mary nearly suffers a miscarriage, she is confined to bed until her child is born. Norfolk recalls Anne to England to keep Henry's attention from wandering to another rival, particularly Jane Seymour. Still deeply hurt by Mary's betrayal, Anne successfully campaigns to win Henry over, showing she has grown more mature since her exile. By withholding her sexual favours, Anne drives Henry to vow to never again bed his wife or speak to Mary. Anne exacts this promise just after Mary gives birth to the much-anticipated son, Little Henry, making her victory hollow. Shortly afterwards, at Anne's suggestion, Henry sends Mary and her son to the country. Shortly after her return, Mary's husband, William, dies from the sweating sickness.
The ambitious Anne encourages Henry to break from the Roman Catholic Church when the Pope refuses to annul his marriage to Queen Catherine, despite Henry's insistence that her marriage to his older brother was consummated. Henry succumbs to Anne's demands, breaks from the Roman Catholic Church, declares himself Supreme Head of the Church of England, and gets Thomas Wolsey to annul his marriage to Katherine. The scandal of Anne's brief marriage to Henry Percy threatens her coming marriage to Henry until Mary, the only one Henry will trust, returns to court and lies on Anne's behalf, assuring him her union with Percy was not consummated.
Despite her plan's success, Anne's schemes drive Henry to breaking point and in a fit of rage, sexually assaults her after refusing to lie with him until they are married. Hurt and confused by the attack, a now pregnant Anne must go through with the unhappy marriage to please her family and becomes the new Queen of England. Mary and Anne reach a reconciliation and Mary stays with her sister at court. She meets William Stafford, a brave soldier in the English army, and the two fall deeply in love.
Despite the birth of a healthy daughter, Elizabeth, Henry angrily blames Anne for his faliure to create a son and legitimate male heir to the throne. He also begins courting Jane Seymour in secret, which doesn't help Anne's slowly crumbling psyche. After she loses a son after birth, a hysterical Anne begs George to impregnate her since Henry will not lie with her. He accepts at first, determined to help his sister, while Mary runs away, disgusted with them both. Before they can go through with it, however, George begins to cry, and Anne decides that they should not sleep with each other. However, George's neglected wife, Jane, witnesses enough of their encounter to become suspicious and hurt . She reports what she has seen and both Anne and George are arrested. Despite the lack of evidence, the two are found unanimously guilty and sentenced to death for treason, adultery and incest. Distraught by news, Elizabeth Boleyn disowns both her husband and brother, vowing never to forgive them for what their greed had done to her children.
Leaving her children in William's care at her country estate, Mary returns to court to plead for her siblings' lives. But, she arrives too late to save George, who is executed in front of a horrified Thomas. Mary begs Henry to spare her sister, referring to Anne as part of herself. The king softens and tells her he would never harm any part of her. Believing that Henry has spared her sister, she leaves to see Anne right before the scheduled execution. The two sisters embrace and truly reconcile with one another. Before she leaves, Anne asks Mary to promise to take care of Elizabeth if anything should happen to her. Mary watches from the crowd as Anne makes her final speech, waiting for the execution to be cancelled as Henry promised. A letter from Henry is given to Mary, which reveals he has decided not to stop the execution and save Anne. It also tells Mary that she was only spared because of his respect for her and warns her never to come to court again. Horrified, she watches as her sister is beheaded. Mary then fulfills her last promise to Anne and leaves court with the toddler Elizabeth.
The closing captions reveal that Thomas Boleyn, disgraced and alone, died two years after Anne and George's executions. Elizabeth Boleyn died a year after her husband while The Duke of Norfolk was later imprisoned in the Tower. The next three generations of his family – son, grandson and great-grandson – were all executed for treason. True to her word, Elizabeth Boleyn never saw or spoke to her husband and brother again. Henry's break from the Roman Catholic church changed the face of England forever. Meanwhile, Mary married William Stafford and lived happily with him and their children away from the royal court for the rest of her life. The captions also reveal that Henry should not have been concerned about leaving England with a strong heir because, in fact, he did: an heir who would rule England for forty-five years and transform it into one of the most powerful nations in Europe. However, it was not the son he desired, but the strong red-haired girl Anne gave him: Elizabeth.
