In 1675 a masque was performed at the Court of Charles II at Whitehall. There the young soldier John Churchill, Groom of the Bedchamber to the King's brother, fell in love with a pretty lady-in-waiting, Sarah Jennings.

John and Sarah have married. Lord Shaftesbury has threatened Charles with rebellion. To appease his Protestant Parliament, Charles has arranged a marriage between Mary and the Prince of Orange.