Sherlock Holmes in The Sign of the Four (Radio)

The Sign of the Four (1890), also called The Sign of Four, is the second novel featuring Sherlock Holmes by British writer Sir Arthur Conan Doyle. Doyle wrote four novels and 56 short stories featuring the fictional detective.
Plot
In 1888, Dr. Watson remonstrates with Holmes about his cocaine usage. Holmes claims he is bored and needs a problem to solve; Miss Mary Morstan arrives with a case.
She explains that, in December 1878, her father, Captain Arthur Morstan, arrived in London, on leave from his post as a convict guard in the Andaman Islands. He requested her to meet him at the Langham Hotel but was not there when she arrived.

Mary contacted Major John Sholto, a former convict guard who knew her father and was living in England; however, he denied having seen Morstan, who was never heard from again. Four years later, Mary answered an anonymous newspaper advertisement, asking for her whereabouts. She then received a valuable pearl in the post, a gift repeated once a year for six years.

With the sixth pearl, she received a letter asking for a meeting, claiming she had been "wronged". Holmes takes the case, and soon discovers that Major Sholto had died in 1882; within a week of his death, Mary received the first pearl. The only further clue Mary can give Holmes is a map of a fortress found in her father's desk, appended with the words "The Sign of the Four: Jonathan Small, Mahomet Singh, Abdullah Khan, and Dost Akbar".

Publication history
The 1892 cloth-bound cover of The Sign of Four after it was compiled as a single book.
Sir Arthur Conan Doyle described how he was commissioned to write the story over a dinner with Joseph Marshall Stoddart, managing editor of the American publication Lippincott's Monthly Magazine, at the Langham Hotel in London on 30 August 1889. Stoddart wanted to produce an English version of Lippincott’s with a British editor and British contributors. The dinner was also attended by Oscar Wilde, who eventually contributed The Picture of Dorian Gray to the July 1890 issue. Doyle discussed what he called this "golden evening" in his 1924 autobiography Memories and Adventures.
The novel first appeared in the February 1890 edition of Lippincott's Monthly Magazine as The Sign of the Four; or The Problem of the Sholtos, appearing in both London and Philadelphia. The British edition of the magazine originally sold for a shilling, and the American for 25 cents. Surviving copies are now worth several thousand dollars.

The Sign of the Four was adapted for radio by Bert Coules in 1989 as part of BBC Radio 4's complete Sherlock Holmes 1989–1998 radio series, with Clive Merrison as Holmes, Michael Williams as Watson, and featuring Brian Blessed as Jonathan Small.