In 1585, Catholic Spain, ruled by King Philip II of Spain, is the most powerful country in the world. Seeing Protestant England as a threat, and in retaliation for English piracy of Spanish ships, Philip plots to take over England and make his daughter, Infanta Isabella Clara Eugenia of Spain, the Queen of England in Elizabeth's place. Meanwhile, Elizabeth I of England is pressured by her advisor, Francis Walsingham, to marry - if she dies without an heir, the throne will pass to her cousin, Mary, Queen of Scots, who is Catholic.