It is the late sixteenth century and Elizabeth I is the protestant Queen of England. Her cousin Mary returns from France to Scotland and is hailed as Mary Queen of Scots, a catholic queen. She is a threat to Elizabeth as she has a claim to the throne of England.

Mary's son James finally succeeds to the English and Scottish throne after the death of the childless Elizabeth but is faced with growing discontent from the Catholics culminating in an attempt by Guy Fawkes to blow up the houses of Parliament and kill the king.