The reign of Queen Elizabeth II is legendary. It started while she was very young and continues now into her 90s. Elizabeth (played by Claire Foy) grew up watching her father, George VI (played by Jared Harris), rule and expected his brother Edward, Duke of Windsor (played by Alex Jennings) to assume the throne. When he abdicates in order to married divorced American Wallis Simpson (played by Lia Williams), Elizabeth becomes the Queen of England.

She has married Philip (played by Matt Smith), who she names the Duke of Edinburgh. Assuming the throne at a tumultuous time would be trying for anyone. The world and England is in a time of war with World War II going on. She and British Prime Minister Winston Churchill (played by John Lithgow) try their best to lead the people. Elizabeth also has to deal with a husband who is not happy with his lack of a role and a sister, Princess Margaret (played by Vanessa Kirby), who is having an affair with a married man.