the scene is of an apocalypse. you were turned away from shelter by "someone".
that person doesn't have a feeling of being "official", so i'm thinking you've
chosen to face the conflagration as if you were responsible for creating it.
the unknown friend is, or is acting as, a 'spiritual guide' in your efforts.
you were instructed that "all [you] will need" is that pen, with a single bullet
in it, so i'm thinking that you'll be expressing some idea, probably here on
this forum, using the power of the pen.