Well, so I was so excited about this development that I stopped reading and fired off the post, and then I got busy with other stuff, and only got back to the novel yesterday, at which point I discovered that the dead guy wasn't Henry at all, but the escaped convict, Selden:
"We must send for help, Holmes! We cannot carry him all the way to the Hall. Good heavens, are you mad?"
He had uttered a cry and bent over the body. Now he was dancing and laughing and wringing my hand. Could this be my stern, self-contained friend? These were hidden fires, indeed!
"A beard! A beard! The man has a beard!"
"It is not the baronet—it is—why, it is my neighbour, the convict!"
With feverish haste we had turned the body over, and that dripping beard was pointing up to the cold, clear moon. There could be no doubt about the beetling forehead, the sunken animal eyes. It was indeed the same face which had glared upon me in the light of the candle from over the rock—the face of Selden, the criminal.
Then in an instant it was all clear to me. I remembered how the baronet had told me that he had handed his old wardrobe to Barrymore. Barrymore had passed it on in order to help Selden in his escape. Boots, shirt, cap—it was all Sir Henry's. The tragedy was still black enough, but this man had at least deserved death by the laws of his country. I told Holmes how the matter stood, my heart bubbling over with thankfulness and joy.The troubling dimension to Holmes's rational zeal is still kinda there--the scene is "black enough," as it were. In fact the issue comes up again a few pages later, when Holmes uses Henry as bait to catch the hound, and the experience is traumatic enough that Henry has to take a trip around the world with his doctor to recover. Clearly, Holmes's primary concern is not with his clients' well-being, except as it represents his success in solving the case. Nevertheless, the ironic edge is considerably dulled. And I have to admit to having been pwned by Conan Doyle, whose main interest is not in Holmes's moral complexity, but in keeping the reader off balance till the end. I was an easy mark because of my literary training; I'm always going to leap into multilayered considerations of Theme whenever the slightest opening is given to me.
Ah, well. Of course, Conan Doyle and his characters also did a good job in selling the false identification, with lots of hand-wringing and self-berating. All of this goes to show us--and them--that nothing, nothing, is as it seems in a Holmes story, not until the last period has landed at the end of the last sentence. That is, looking at a piece of evidence once is not enough. Looking twice may not be, either. And one's emotions, even for Holmes, can get in the way of remembering this basic fact. In this instance, Conan Doyle used his detectives' overwrought emotions, which were especially surprising in Holmes's case, as a sleight of hand to distract the reader. We all forgot to look at the dead man's face.
I think that's a good and impressive technique that mystery (and literary mystery) writers can use. But probably only once in a novel.