Based on

Movies like Murder by Decree (1979)

Sherlock Holmes is drawn into the case of Jack the Ripper, who is killing prostitutes in London's East End. Assisted by Dr. Watson, and using information provided by a renowned psychic, Robert Lees, Holmes finds that the murders may have their roots in a Royal indiscretion and that a cover-up is being managed by politicians at the highest level, all of whom happen to be Masons.