The undead amass as they seek the epicenter of an earthquake. Aftershocks ensure they stay on course, drawn to the origin of the ground-shaking waves. Acheron sits in the path of the horde, and the residents have little ammo to spare. They prove they will defend the camp at all cost, taking extreme measures to protect Acheron from being overrun.

Acheron survivors, both inside and outside the gates, fight to stay alive, working with too few bullets to fend off the thousands of undead. Inside, they wait for their leader's return from Memphis, hopeful for news of a cure. Those outside seek to return to the safety of Acheron, including Ethan, who proves he's a force to be reckoned with.

The survivors, exhausted and injured, scattered far and wide, fend off the undead, vengeful Bowlin brothers, collapsing houses, and radical fanatics, but as they encounter more and more undead moving south, they face the reality that not even Ethan has enough bullets.