There come those moments in the career of Sherlock Holmes when he takes a turn for the dark.
All the logic, professional focus, patriotism, and virtue need to go away for a time in pursuit of a victory can will apparently only come from cheating. And what case comes to mind when we consider Sherlock Holmes taking that darker path?
The business of Charles Augustus Milverton.
"Surely you have gone too far," Watson says. Sherlock Holmes just courted and proposed to a girl he has no intentions of a relationship with.
"For heaven's sake, Holmes, think what you are doing!" Watson cries, not five minutes later. Sherlock Holmes is planning a break-in.
"I cannot help you, Lestrade," Sherlock says at last, and covers up a murder.
True to their form of taking the originals and ratcheting them up a bit, BBC Sherlock even took that last bit and just had Sherlock Holmes commit the murder himself, forcing his brother to cover it up.
Sherlock Holmes carries a real Superman/Batman duality in his character that is a part of what makes him appeal to both sides of human nature. In the daylight, he is a paragon, a hero at a level of ability we can aspire to, using his powers for truth, justice, and the British way. But in the night? A vigilante whose actions would land him in jail if he were ever caught by the police.
"Vigilante," of course, is our word for "criminals we like."
Most of us believe in the systems and legally laid-out moral codes that define our nations on a large scale, and our communities on a smaller scale. But we also can't help but see there are flaws in those systems, mis-steps in the code that allow those with no kindness or an over-abundance of selfishness to do harm in pursuit of wealth, power, or just to fluff up their own view of themselves.
Charles Augustus Milverton embodies all three of those motives, taking profits, yes, but with a power dynamic that plainly feeds his ego and gives him that creepy smile. Perhaps the most disgusting thing we see of him is the sheer happeniness he enjoys during his blackmail demands and verbal jousting as he plays his power cards. So we give Sherlock Holmes certain moral freedoms when it comes time to deal with Milverton.
Sherlock Holmes does wrong, yes. But to stop a larger evil.
Defining "a larger evil" in fiction is quite easy. You add that Milvertonian twinkle to the eye, maybe have his TV incarnation lick people's faces. But in the real world, of consequence and secrets harder to keep hidden? A Sherlock Holmes taking such action might have a harder time of it.
Still, Holmes's cases always give us a broad range of human situations to contemplate. And when he gets his hands dirty, as in Charles Augustus Milverton's case, that discussion can be very well worth having.