Doctor Who: 10 Storylines That Will Never Be Revisited

Listen is one of Doctor Who's biggest "Marmite" episodes in that it will either click with you, or it won't. It's purposefully abstract, potentially confusing and definitely a little odd, if only for the fact that the majority of the runtime finds the Doctor going crazy trying to track down an enemy that might not even exist.

This is because he's hypothesised that - somewhere out there - there must be a creature that is perfect at one thing, and one thing only: hiding. But if that were the case, how would we even find such a creature? Wouldn't it be permanently concealed? Fittingly, we never actually see a monster in the episode, except for one hotly-debated moment in which an unidentifiable mass can be seen hiding underneath a bed sheet.

This is the first and only clue we are given as to the nature of the Listen creature - if one even exists to begin with. So what was underneath the sheet? Was it a Silent, a popular theory among Who fans? Was it something brand-new? Was this all some sort of dream sequence or other fake-out?

The episode is now over five years old and this concept still hasn't been revisited, and given that the story established that the Doctor's quest to discover this creature stemmed from a childhood fear of "the monster under the bed", the creature was always meant to be an abstract force, rather than a tangible, physical threat.

Or, to put it another way: we'll never know what was under that sheet.