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.