Humanity has pushed itself to the brink of extinction. After a deadly series of internal wars, most of Earth is now an uninhabitable, monster-infested wasteland. All hope seemed lost until an alien society, the Pan-Galactic Republic, came to the rescue, building Sunflower City as a safe haven. This is humanity's last chance for survival.

However, not everyone accepts this new inter-species relationship, and a dangerous movement is rising up to compromise humanity's survival yet again. In the midst of this terrifying conflict, an unexpected individual ends up as the only hope for stopping the carnage to come: the Man from Rock Bottom. But will this accidental hero be enough to save Earth itself from planet-wide murder-suicide?