Clean Air

Centuries after the surface of the earth was devastated by an unknown disaster, the remnants of humanity live in a series of vast underground silos, each unaware of the existence of the others.

For the inhabitants of Silo 34, the silo is the world, and the only world they know. Questions about the outside world are forbidden, and asking them is what got Dean Winchester's parents killed. He isn't even sure himself that they weren't crazy.

That all changes when he hears a voice on the radio -- a voice from another world.