Joshua is 13. He lives with his mother and step-father in Amarias, an isolated town on top of a hill, where all the houses are brand new. At the edge of Amarias is a high wall, guarded by soldiers, which can only be crossed through a heavily fortified checkpoint. Joshua has been taught that beyond the concrete is a brutal and unforgiving enemy, and that The Wall is the only thing keeping him and his people safe. One day, looking for a lost football, Joshua stumbles across a tunnel which leads towards this forbidden territory.