10 Dropped Doctor Who Plot Threads We'll Never Get Answers To

Sleep No More is a standalone episode in a series that's stuffed with two-parters, so it's actually quite funny that it concludes with a cliffhanger.

At the very end of the story, it's revealed that narrator Rassmussen is actually one of the Sandmen, villains that are made up of that crusty stuff you find in your eyes after a long sleep. Yes, really. Turns out that Rassmussen edited the whole episode together himself, found footage style, embedding a signal within the video that will convert anyone who watches it into a Sandman too.

He finishes by saying that he's going to broadcast the episode to the whole solar system, meaning that billions of people could potentially watch the footage, transforming them into Sandmen and basically destroying the Earth as a result.

So what happened after this point? Did Rassmussen's plan work? Was the entire solar system turned into a Sandman playground? We just don't know.

At one point, writer Mark Gatiss was planning to do a sequel to this episode in Series 10, indicating that he had a bigger story planned. However, he ended up writing Empress of Mars instead, leaving Sleep No More's ending unresolved.