—“The Adventure of the Blue Carbuncle”
“A Scandal in Bohemia” proved that even Sherlock Holmes can himself be tricked.“The Man in the Twisted Lip” shows us the great detective can, even with his brilliant powers of deduction, also be guilty of jumping too hastily to an erroneous conclusion. “The Boscombe Valley Mystery” shows us a Holmes who is willing to keep a incriminating secret, even from the police, to aid or protect a client, though we must use the term “client” loosely. In fact, it is exactly this issue that Dr. Watson raises upon paying a social call to Holmes during Christmas of 1890, going so far to remark to Holmes that "so much so…that of the last six cases which I have added to my notes, three have been entirely free of any legal crime."
As “The Adventure of the Blue Carbuncle” unfolds, there is, eventually, the revelation that a crime has been committed, but there is no client, no case, and finally, ultimately, no culprit. The supposed “villain”, if one were to hew a bit too closely to the formula of the mystery or adventure story, “gets away with it,” with the blessing of Holmes, the man who deduced the would-be criminal’s comeuppance.
As we have seen in “Bohemia,” “Twisted Lip” and “A Case of Identity,” Holmes’ motivations are purely his own, his skills deployed strictly to satisfy his obsessions, and not at the pleasure or command of Scotland Yard or any other authority. Despite this reasoning, oft-repeated by Holmes throughout the canon, for some it just seems odd that Holmes would, after uncovering the crime, allow the criminal to go free. But this is precisely what occurs in “The Adventure of the Blue Carbuncle,” much to the confusion of some Sherlockian scholars. Notable member of the Baker Street Irregulars, Lloyd R. Hedberg Jr. has suggested that Holmes identifies a real culprit in his interrogation of the otherwise harmless accomplice whom he sets free:
In the end, the explanation Holmes gives for letting [the criminal] go is singularly feeble and unconvincing. He seems to be as much trying to justify it to himself, as he is trying to convince Watson…We can be charitable toward our Watson, taking our clue from this very chronicle. "It is the season of forgiveness."
Holidays can certainly bring out the best in people. But we are more inclined to think that, rather than Holmes finding himself in the grip of some particularly Dickensian Christmas spirit, it is a matter of simple economy. If there are no criminals in the world in which Holmes finds himself, there are no crimes. Crime, for Holmes, is the source he has found for the puzzles he craves. It is a world that, in order to have puzzles, must also have its puzzlers.