In 1886, Sherlock Holmes (James D'Arcy) helps actress Rebecca Doyle (Gabrielle Anwar) get rid of blackmailer Professor Moriarty (Vincent D'Onofrio), chasing the criminal to his apparent death. Holmes' success makes headlines, and he is hired by a drug dealer, Ben Harrington (Struan Rodger), to find the serial killer who's murdering other drug pushers. While examining the bodies with coroner Dr. Watson (Roger Morlidge), Holmes suspects that Moriarty is alive and behind the killings.