When terrorists nuke the US heartland-killing over two million people and destroying massive food stores-the country faces one of its darkest times in history. Food shortages cause rampant hunger and theft, resulting in a deep economic depression. "Food crimes" are declared a serious offense, and the government has thousands of additional criminals it can't incarcerate.

The solution lies in the wasted heartland, which the government designates as the US Central Penitentiary. To make room for the food criminals, all current prisoners with life sentences are sent to the radioactive site hidden behind a wall of refuse and debris that surrounds the blast center. Although the government initially provides them basic essentials, the prisoners must survive and govern Pen Central on their own.

Now seventeen years after the nuclear attack, the US government decides to reclaim the land but has lost contact with the prison. When all attempts to gain intel on its status are thwarted, Chris and Kelly Elliot, a young Midwestern couple facing life sentences, are recruited as spies. In exchange for the government protecting their twin daughters, they must venture beyond the Wall to Pen Central and report their findings. But what they discover defies their imaginations and puts their allegiance to the ultimate test.