Lady Mary's father is innocently accused of treason and is executed. It is the king's evil chancellor, the duke of Brampton, who has found a way of getting rich by accusing his enemies of treason, having them killed and then expropriating their fortune. Lady Mary travels to London to meet the duke, but instead meets the handsome highwayman Michael Dermott. Dermott has found the duke's notebook where all his evil schemes have been written down.