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| 2 | List of Sherlock Holmes episodes - The Return of Sherlock Holmes (1986–1988) |  |  |  |  |
| 3 | No. | Title | Based on | First broadcast | Synopsis |
| 4 | 14 | "The Empty House" | "The Adventure of the Empty House" | 9 July 1986 | Holmes returns to England, to Watson's shocked surprise, and must stop a member of Moriarty's gang who is trying to assassinate him. |
| 5 | 15 | "The Priory School" | "The Adventure of the Priory School" | 16 July 1986 | A rich duke reluctantly allows Holmes to search for his ten-year-old son who is missing from his boarding school along with the German tutor. |
| 6 | 16 | "The Second Stain" | "The Adventure of the Second Stain" | 23 July 1986 | The Prime Minister asks Holmes to help recover a stolen letter which could lead to war if released. |
| 7 | 17 | "The Musgrave Ritual" | "The Adventure of the Musgrave Ritual" | 30 July 1986 | While vacationing at the estate of his old university classmate Sir Reginald Musgrave, Holmes is called in when the scholarly butler disappears after being discovered reading an old document about a mysterious family ritual. |
| 8 | 18 | "The Abbey Grange" | "The Adventure of the Abbey Grange" | 6 August 1986 | Lord Brackenstall has been murdered and his battered wife says that a thief and his sons were the culprits: wine glasses convince Holmes otherwise. |
| 9 | 19 | "The Man with the Twisted Lip" | "The Man with the Twisted Lip" | 13 August 1986 | Watson finds Holmes in an opium den, where he has been sent to look for Neville St Clair, who is suspected to have been killed by a beggar. |
| 10 | 20 | "The Six Napoleons" | "The Adventure of the Six Napoleons" | 20 August 1986 | Holmes is contacted by Inspector Lestrade after the police are baffled by a series of burglaries serving only to steal and smash identical busts of Napoleon. |
| 11 | 21 | "The Sign of Four" | The Sign of the Four | 29 December 1987 | Mary Morstan has received a pearl in the post every year since her father's disappearance; this leads Holmes and Watson to the truth about a secret pact between four convicts during the Indian Rebellion of 1857. |
| 12 | 22 | "The Devil's Foot" | "The Adventure of the Devil's Foot" | 6 April 1988 | In Cornwall, Holmes investigates when a woman mysteriously dies with a horrified look on her face and her two brothers are driven insane. |
| 13 | 23 | "Silver Blaze" | "The Adventure of Silver Blaze" | 13 April 1988 | Holmes investigates when a prized racehorse goes missing and his trainer is found bludgeoned to death. |
| 14 | 24 | "Wisteria Lodge" | "The Adventure of Wisteria Lodge" | 20 April 1988 | An amateur cartographer who stayed with another map enthusiast seeks help when his host vanishes in the middle of the night. |
| 15 | 25 | "The Bruce-Partington Plans" | "The Adventure of the Bruce-Partington Plans" | 27 April 1988 | Holmes helps Mycroft when stolen top secret blueprints for a submarine are found on the body of a civil servant found dead on the tracks of the Underground. |
| 16 | 26 | "The Hound of the Baskervilles" | The Hound of the Baskervilles | 31 August 1988 | Sir Charles Baskerville was found dead with a horrible expression on his face after seeing a mysterious demonic spirit of a gigantic hound that has haunted his family. |

Question: What dates did "The Sign of Four" and "The Hound of the Baskervilles" aired, respectively?
Answer: "The Sign of Four" and "The Hound of the Baskervilles", aired on 29 December 1987 and 31 August 1988 respectively.