From the introduction:
For as long as you’ve been alive you’ve only known the dark of the sewers and subways. The surface and the sunlight are a rare sight for living men in these days. The world around you is a ruin. The air on the surface is poison to your lungs. The water is dirty, sickening. The inhabitants are blind, bloodthirsty mutants and demonic looking dragons.
And today, this is the world you prepare to face. Your home, the Enclave, has begun to run short of food. And the last Rangers sent up top haven’t reported back with more. You are of age, and your name has been tossed into the lottery, and lucky for you it was drawn.