The makers of these Granada episodes dedicated themselves to producing the entire Holmes canon. Unfortunately, some of the stories are not very good, and the wonderful Jeremy Brett didn't survive to the end. When the series aired on Masterpiece Mystery, it was introduced by Vincent Price. His presentation at the time pointed out that we were in for some real suspension of disbelief if we were going to enjoy the episode. Conan Doyle was basically a scientist, but this is really more science fiction than detective work. Because I know that early fiction writers often made assumptions that proved medically unsound (the blood transfusions in Stoker's Dracula, for example), I can still watch and enjoy. The conclusion floored me. I had not read this story and so I wasn't prepared. It is both startling and really laughable. Jeremy Brett at one point delivers one of those awful pronouncements, more indicative of Basil Rathbone. Brett had pretty much let the pontificating go. Far from the best, but fun nevertheless.