Lord Harry is really Henrietta Rolland, a young lady who has assumed the guise of a gentleman to track down and kill Jason Cavander, the marquess of Oberlon, the man she believes responsible for her brother Damien's death at the Battle of Waterloo. She wants to challenge him to a duel. When he's lying at her feet, then and only then will she tell him why she's killed him, and who she really is. Unfortunately, there's a really big snag.