As the mystery of the 'Twelve Caesars' deepens, Holmes is reunited with a woman from his past with heartbreaking news for the young sleuth. While Watson follows a hunch, the good doctor closes in on the identity of the serial killer terrorizing London when an intended victim is spared an ignoble end! Unfortunately, the mad murderer will not be satisfied until a dozen deaths are done, even if it means slaying someone close to the intrepid detectives!