On hearing of the death of his only son by the sword of Paul Déroulede, the Duc de Marny forces his daughter Juliette to swear an oath to ruin Déroulede in revenge for her brother's death. Having tricked her way into Déroulede's home Juliette denounces her host, but realizes to late that she has come to love the man she has vowed to destroy. She will need a help of Scarlet Pimpernel to save the day.

Baroness Emmuska Orczy (1865-1947) was a Hungarian-born British novelist and playwright. She is best known for her series of novels featuring the Scarlet Pimpernel, the alter ego of Sir Percy Blakeney, a wealthy English fop who transforms into a formidable swordsman and a quick-thinking escape artist, establishing the "hero with a secret identity" into popular culture.