The Hounds of Baskerville order to test his theory. He also points out Sherlock was wrong for once; he believed the drug was in Henry's sugar and put it in John's coffee. In the closing scenes, Mycroft oversees the release of Jim Moriarty (Andrew Scott) from a holding cell in which he has written Sherlock's name all over the walls. The story is based on Arthur Conan Doyle's novel "The Hound of the Baskervilles", and also contains plot devices and lines from other Doyle stories: In June 2011, it was announced that Russell Tovey would appear in "Sherlock" series two in its second episode.
The Hound of the Baskervilles (1939 film) Henry Baskerville (Richard Greene), the last of the Baskervilles, heir to the Baskerville estate in Devonshire. Dr. Mortimer is anxious about letting Sir Henry go to Baskerville Hall, owing to a supposed family curse. He tells Holmes and Watson the legend of the Hound of the Baskervilles, a demonic dog that first killed Sir Hugo Baskerville (Ralph Forbes) several hundred years ago (seen in flashback) and is believed to kill all Baskervilles in the region of Devonshire. Holmes dismisses it as a fairy tale, but Mortimer narrates the events of the recent death of his best friend, Sir Charles Baskerville,