Here's a bizarre episode, that I did not enjoy for the most part, yet it redeemed itself at the end.
While I was watching, I kept thinking of the old series The Prisoner. Wasn't there constant maniacal laughter throughout that show? With confusing, psychedelic visuals? Maybe it was just one episode.
In any case, as you're watching Sherlock in his drugged, incomprehensible state, you can't tell what is real and what he is imagining.
Somehow, the plot moves along and you're pretty sure he is actually seeing through the haze to the truth, and a cuddly looking little bear of a philanthropist probably really is a serial killer.
Flaw in the telling this week:
I know you have to write it off to Sherlock's reduced ability to observe and comprehend, but I feel Sherlock's analytics were working well enough so he'd notice the artificial lenses worn by the murderer's "daughter," and that she clearly did not need the cane she carried at all. He spent a lot of time with her and he would not have missed these things among many others.
I was pleased to see Mary back haunting Watson's psyche, what a waste of a great character to kill her off. That final scene!!! where Watson confesses to her that he cheated with the woman on the bus in a texting relationship, (sniff) that was so heartbreaking. Even Sherlock was moved to give him a hug. (sniff)