If The Adventures Of Sherlock Holmes were broadcast in America first, this would have debuted at Christmas time rather than in June of 1984 when it did. Arthur Conan Doyle might very well have been influenced by that other immortal English writer Charles Dickens when he wrote the Blue Carbuncle.
The Blue Carbuncle is not some ugly growth on someone, but a rare and priceless blue diamond which some opportunistic thieves stole from the Duchess of Moncor. The only part of the crime that went well was that the blame got placed on some guy who had a criminal record, but was innocent of this caper.
When Holmes and Watson are called in the trail of the missing gem leads to some very interesting places and where the jewel wound up is pretty funny. And how it got there is a testimony to the quick, but faulty thinking of the real perpetrator. But as I said the perpetrator was not very bright.
The thing to remember is that it is Christmas time when this case occurs and that fact enters into Holmes's thinking when he finds the perpetrator. What to do with this fool, let's just say that Christmas enters his thinking.
You won't believe where the jewel was hidden.