Disclaimer: Blah, blah, I don't own Doctor Who, its characters or objects etc. I imagine this is the most boring part of most fanfics.

Plot: Xena, a human colony, is the heart of trade and marketing in the universe, with species of all kinds descending upon Xena for exotic products and cheap goods. So, when the Doctor decides to take Amy there for a visit, you can imagine his surprise at how deserted the place is. But it gets worse for them. Xena is stuck in constant darkness and the last inhabitants of the colony have been forced underground. Can the Doctor save the survivors? What happened in the first place? Within time, it becomes clear to the Doctor, that the situation is the worst possible and he is dealing with what he thought was a ancient Time-Lord myth...

Ladies and gentlemen, this is the Longest Night and something is lurking in the darkness.