The Man in Black fled across the desert, and The Doctor followed...
Doctor Who is an interesting show to be a fan of as an adult. In the UK it is promoted as a "family program," an idea that has largely fallen out of vogue here in the United States. Here entertainment feels much more divided between children and adult. Outside of the Marvel Cinematic Universe, there is very little genre entertainment being produced that is suitable for people of all ages.
The Doctor though, is different. He tries to appeal to a large fanbase that spans decades in age. It is after all, a show that has been on the air for over fifty years. That can lead to some tonal inconsistency, as one episode might deal with Robin Hood fighting robots, while the next will be about how being functionally immortal will slowly destroy whatever sense of morals you might have. It's a disconnect that a lot of people have trouble reconciling in their minds, but if you allow yourself to be charmed and lulled by the sillier adventures, then when the show does take a turn towards the dark, its effects can be all the more powerful.
The most recent episode, Heaven Sent, is a tour de force for star Peter Capaldi. He is the only actor on screen for 95 percent of the hour, with only a faceless monster to bounce off of. It is a puzzlebox mystery, the kind that show runner Steven Moffat excels at, and that both delight and infuriate viewers in equal measure. The Doctor has been transported to castle prison that is constantly rearranging it's rooms and it corridors, Hogwarts by way of Steven King's Dark Tower. As he makes his way through the castle, it increasingly becomes clear to both him and the viewer that he has done all of this before. In fact he has performed the same actions over and over again for the past seven thousand years. How this is possible is a neat piece of technobabble about teleportation and the difficulty of killing a Time Lord. It is easily the best episode of this Doctor's run and maybe the best episode of the entire new era of Doctor Who, give or take a Blink.