The Elusive Pimpernel S01 E06 The Dauphin in the Tower

Foppish Sir Percy Blakeney, who secretly leads a double life as the daring rescuer of French aristocrats from the guillotine during the French Revolution, fights to save his brother-in-law while his wife is manipulated by the villainous Chauvelin into helping capture him, unaware of her husband's true identity.