It is certainly an interesting concept, and there's nothing like a newly discovered prophesy to kick-off a story. I'm looking forward to finding out more about the worlds and the Town, as well as Nat's son and the story behind that.

There are a few technical issues, such as switching from Third Person POV to First Person POV in one paragraph. Or not italicizing character thoughts, and a few other things easily corrected through edits. Maybe because Nat is such a closed-off character, but I'm not getting a sisterly vibe between them. It feels more like a subordinate-superior relationship, especially how she describes Nat never going on runs, and being a 'big gun'. If it was sisterly, there would be more interplay between the characters, perhaps bantering--even if it's only one-sided. Right now it feels uncomfortable, and Andy trying to console her comes off as a little awkward and out of place. The age gap lends to this.

In all, though, good job.