Sherlock Holme must track down his nemesis Professor Moriarty after the villain kidnaps Holme's brother Mycroft. The evil doctor is forcing his captive to decode highly classified military documents.\
Sherlock Holmes (Peter Cushing) has retired. But when MacDonald (Gordon Jackson) asks him to take on another case, he says yes. There have been some mysterious murders, and there are no visible causes for the deaths. At the same time Holmes gets this case, Graf Udo Von Felseck (Anton Diffring) gives him another case: find a young and missing prince to prevent war between Germany and England. But Von Felseck is not as honest as he seems...
Sir Charles Baskerville dies on the moor under mysterious circumstances and rumors abound about a demonic hound. When the American heir arrives to take charge, a family friend calls in Holmes and Watson to get to the heart of the mystery.
For years, a blackmailer has been preying on the weaknesses of others throughout London. When Holmes hears of the utter misery this mystery man is creating, he adopts a campaign to thwart his evil scheming. The campaign astonishes Dr. Watson by its strangeness and finds Holmes falling in love.
Sherlock Holmes investigates strange and tragic happenings in a village that appear linked to a man who seems to be like a vampire.
Sherlock Holmes' problem with disturbing dreams proves to be both an impediment and an aid in the search for a missing woman.