In a world that lost its sun, humanity huddles in small towns around wells of light, shafts leading to the world's core that glow with the light of the lava below. One plant still grows, manna, a rice sized, oily leaf that falls from the sky with the rains and sustains all other life. Silas is a streetsweeper, gathering fallen manna and delivering it to the oil presses to be converted to fuel for the fires of Bastion. A chance encounter sends him out of the city, and into the darkness that is Umbra.