Since there have been tweets implying that the upcoming Sherlock special could involve 'The Adventure of the Blue Carbuncle', and since I had already purchased 'The Adventures of Sherlock Holmes', I set to reading that particular story.
When looking at it in hindsight, the case seems fairly simple, but I found it engaging anyway. Mostly, I loved the ending. I could indeed picture our modern day Sherlock letting a thief go free and saying: "It's Christmas" (nod to past times when he used the phrase in a completely different context). And it's such a merciful gesture - though not at all law-abiding - that it fits with Sherlock's character arc.
My favorite line is this: "I suppose that I am commuting a felony, but it is just possible that I am saving a soul."