a dying world

The sun was supposed to turn into a red giant 10 billion years from now, however the suns life cycle had ended early and it started to expand killing basically all life on earth...except for a few very unlikely people, you along with 1000 people live in a bunker deep beneath the earths surface however just because your in a safe house doesn't mean you are safe as sometimes you have to venture into the dangerous surface that has been melted by the suns intense heat.