As a lead-up to “The Sign of Three,” the new Sherlock episode airing tonight, here are some facts about the Conan Doyle story on which it is (presumably) based: “The Sign of Four.”
1) It is the second Sherlock Holmes story written, though chronologically it takes place several years after Holmes and Watson first meet. Like “A Study in Scarlet,” it’s long enough to be separated into chapters.
2) In this story, we learn for the first time that Holmes is a drug addict. (Cocaine and morphine, his stimulants of choice, were not yet illegal at the time, but Watson is still concerned as a doctor about their effects on Holmes).
3) Sherlock’s method of deducing everything about John from his phone in “A Study in Pink” is taken from this story, where Holmes gets more or less the same clues from Watson’s watch.
4) This is the story in which Watson meets his future wife, Mary Morstan.
5) It is the first story in which Holmes uses his famous maxim (repeated often in later stories): “When you have eliminated the impossible, whatever remains, however improbable, must be the truth.”
It’s a pretty romantic and sensational mystery involving murder (of course), a damsel in distress, a lost treasure, an island savage and a consiracy complete with a secret symbol. The trailer for the BBC version didn’t tell me anything about how closely “The Sign of Three” will follow it. We do know John is marrying Mary in this episode, so that’s one connection to the original, but other than that–we’ll just have to wait and see. Four hours to go! Namarie!