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 obvious to him that it was Mrs Barrymore, but her husband denies it. Watson can find no proof that Barrymore was in Devon on the day of the chase in London. He meets a brother and sister who live nearby: Mr Stapleton, a naturalist, and the beautiful Miss Stapleton. When an animal sound is heard, Stapleton is quick to dismiss it as unrelated to the legendary hound. When her brother is out of earshot, Miss Stapleton mistakes Watson for Sir Henry and warns him to leave. She and Sir Henry later meet and quickly fall in love, arousing Stapleton's anger;