2. The Baskerville Agent
![Baskervilles](https://cdn3.whatculture.com/images/2013/12/Baskervilles.jpg)
In the previous episode, the hound of the Baskervilles was revealed to be in actual fact, a hallucinatory agent. This is despite a rather unnerving scene with a dog's eyes following Watson around the room; we don't actually see the creature, but the direction certainly implies that it's real. What if Sherlock administered these drugs to John? The impending death of Holmes could've been implied via the various "I owe you" references, or simply from the direction that the story was heading. It's massively unlikely, and of course, Watson's not the only one who needs fooling here. It's also a long-shot that the same hallucinatory agent should appear in the very next episode. But the technique of showing the events from Watson's distorted point of view is one that's already been used. Which leads onto the altogether much more likely theory that...