A new and strange assignment sends Nick and Ishi off on an uncharacteristic job for them: a search for the Ripper's blade. Looking into one of history's biggest unsolved mysteries, however, soon turns into a mystery of their own. In London, their investigations into the common theories behind the Ripper murders take a bizarre turn as they uncover an unexpected twist to the motives behind the killings. Nick and Ishi soon find themselves in the middle of uncovering a possible nineteenth century cover-up involving a secret society of women called the Kharites, who were active in London at the time.