Doctor Who: 12 Cool Details Russell T Davies Just Revealed About New Earth & Gridlock
5. The Episode Was Inspired By An Edgar Allan Poe Story About A Deadly Disease
The idea for Gridlock partly came from Davies' desire to revisit New New York, but another big inspiration for him was The Masque of the Red Death, a short story by famed writer and poet Edgar Allan Poe.
In this story, a group of upper-class citizens seal themselves in an abbey in order to escape a disease called the Red Death. These wealthy nobles don't really care about the rest of the common people outside the walls of the abbey: they just want to wait out the Red Death in a luxurious and comfortable environment.
Davies then took elements of this plot - the rich and the poor separated, a deadly disease - and came up with Gridlock. In his version though, he decided to kill off all the rich people, telling his story from the point of view of the commoners.
He also threw in some giant crabs, for good measure.