The Other Boleyn Girl is a 16th century soap opera. At the beginning of the story Sir Thomas Boleyn learns that King Henry VIII’s marriage is on the rocks. Naturally he orders his daughter Anne (Natalie Portman) to try to become the King’s mistress. She agrees readily enough, but unfortunately the King’s eye falls instead on Anne’s gentle, pure-hearted younger sister Mary (Scarlett Johansson.)
I presume most readers will know the rough outlines of what is going to happen: Henry VIII marries Anne Boleyn and the marriage ends badly, but not before producing the future Queen Elizabeth I.