This one was published in October 1921, and while the date of the story is unknown, we, and the page boy Billy, are assured by Watson that the ploy being discussed has been used once before, which we’ve seen in “The Adventure of the Empty House,” marking Holmes’ return from the Great Hiatus. Remember that story, because we’ll swing back around to it before this is over. The ploy in question regards a wax effigy of Holmes that is positioned in the front window and moved around every now and again so that, from the outside, he appears to be at home. The idea is to give a would-be murderer with a rifle a decoy target to shoot.
The murderer in question is named as Count Negretto Sylvius, a diamond thief Holmes has been following in disguise. Holmes gives Watson the criminal’s address and sends him out the back for the police. The Count arrives and is invited in by Billy per Holmes’ order. The Count makes an attempt on the effigy, and Holmes takes him by surprise. In one of the more impressive tête-à-tête displays in the canon, Holmes offers the Count freedom if he gives up the missing jewel, otherwise jail, a proposition the Count can discuss “in private” with his associate, boxer Sam Merton. Holmes steps into the next room to give them privacy while playing his violin for five minutes.
Leave it to Holmes, however, to have an ace up his sleeve. The Count opts to double-cross Holmes, and when he takes the stone from his pocket to show Merton by the light near the window, Holmes leaps from the chair where his effigy previously sat and grabs it away. How’d he do that? Elementary. His bedroom has a gramophone and a secret passage that leads behind the curtain. Of course it does.
The police arrive and arrest the bad guys. Lord Cantlemere, who did not want Holmes involved, insists on the arrest of whomever is found to possess the jewel… which he finds in his pocket where Holmes has placed it. For his part, Holmes apologizes, but it’s hard to begrudge the man a little fun with his antagonists.
For those who like to keep track of such things — you know who you are — this is one of only two short stories in the canon written in the third person, the other being “The Last Bow.” The reason this one’s in third person is the same reason it’s largely confined to the single room at Baker Street: because the story was adapted from a stage play (as opposed to the other way around). The plot twist where Holmes reveals he listened in while the criminals talk shop wouldn’t be possible in the standard first person Watson narrative, and it would sort of fall flat had Holmes narrated. In the original play, Watson barely appears, hence the decision not to use him to narrate. But wait, it gets better! The nemesis in the original play isn’t Count Sylvius, but rather Colonel Sebastian Moran, right hand man of Moriarty and sharpshooter extraordinaire from the aforementioned “The Adventure of the Empty House.” Puts a nice bow on that gift wrapping, doesn’t it?