When an alert goes out to the paying members of the disaster bunker known as New Eden, recently wealthy yet highly dysfunctional Geoffrey and Portia Thompson grab their survival bag, let the staff of their palatial Plymouth Commonwealth estate go, and make the short journey to the rest of their lives. Joining them are one thousand additional souls, destined to repopulate the Earth and rebuild their once great world.

Shortly after arriving and securing the hatch for good, communications to the outside world are cut off. Everyone is convinced this is the end, to include Portia who has vowed to divorce Geoffrey and destroy everything he holds dear. With rations implemented and nerves shot, Geoffrey and his new friends volunteer to travel to the surface to gather information and see if they can leave New Eden.

When they exit the shelter, however, they find a vastly different world. Gone is their reality, and in its place their worst nightmare. With no choice but to escape, they make a run back to New Eden where yet another nightmare awaits...beneath Gehenna.