There's the scarlet thread of murder running through the colourless skein of life, and our duty is to unravel it, and isolate it, and expose every inch of it.
One of the things I want to do this year is work through Sherlock Holmes, so that brings us to the first two, A Study in Scarlet and The Sign of the Four.
A Study in Scarlet, the first appearance of Holmes and Watson, was published in 1887 in Beeton's Christmas Annual. Conan Doyle had thrown it together in three weeks, and it had been rejected multiple times; he got a grand total of £25 for the entire thing. It was published in book form in 1888 by Ward, Lock, & Co.
The Sign of the Four, sometimes also titled The Sign of Four, started over dinner with a number of notables. The most famous person at the table was Oscar Wilde, but there was also an editor, Joseph Stoddart, who wanted to expand the very popular Lippincott's Monthly Magazine into England; in the course of the conversation, Conan Doyle, who was already well known for his short stories, promised to contribute to it. The Sign of the Four was published in February 1890 and J. B. Lippincott & Co. published A Study in Scarlet in American later that year.
History is sometimes made quietly. Neither book did badly, but neither made a big splash, either. But they both set the stage for the short stories, which Conan Doyle began writing for Strand Magazine in 1891, which made them both famous after the fact.
Looking at old time radio episodes, it looks like A Study in Scarlet was adapted for radio in 1962 for The New Adventures of Sherlock Holmes (with the inimitable Basil Rathbone as Holmes) and in 1977 for CBS Radio Mystery Theater; The New Adventures adapted The Sign of the Four in 1963, and CBS Radio Mystery Theater did it in 1977. In general, New Adventures tends to adapt quite loosely and Mystery Theater more strictly, but in any case I hope to listen to all four, if I have the time. [Having looked into it, some of this seems to be due to the fact that various lists often don't make adequate distinction between different Sherlock Holmes shows; which I should have suspected immediately, since 1960s is way too late for The New Adventure. I'll be looking into other OTR episodes, though.]
