As the episodes are named after lines in Milton's poem "Paradise Lost", The Fall refers to that of Lucifer.
The Falls Road is the main road through west Belfast, Northern Ireland,
In series one, episode three, Spector writes the following in his journal:
"Between the idea
And the reality
Between the motion
And the act
Falls the Shadow..."
This is part of a poem by T. S. Eliot called The Hollow Men. He then writes:
Is it the murder
or the shadow of murder
that causes the greatest pleasure,
the greatest pain?