Cardinal Lorenzo Campeggio arrives in England to set up a Legatine court to try the case of the validity of Henry VIII's marriage to Catherine of Aragon. However, this task is complicated by the rapidly changing political situation: as he arrives, he discovers that during the period of his journey, Charles V has once more become the dominant force in Italy, and Pope Clement VII has been compelled to make peace with the Emperor to save the Medici family from ruin.