Set during the Tudor dynasty period in the late 15th and 16th centuries of English history, When Knighthood Was in Flower tells the tribulations of Mary Tudor, a younger sister of old King Henry VIII of England who has fallen in love with a commoner. However, for political reasons, King Henry has arranged for her to wed neighboring King Louis XII of France and demands his sister put the House of Tudor first, threatening, "You will marry France and I will give you a wedding present – Charles Brandon's head!"