Joshua lives with his mother and step-father in Amarias, an isolated town, where all the houses are brand new. Amarias is surrounded by a high wall, guarded by soldiers, which can only be crossed through a heavily fortified checkpoint. Joshua has been taught that the Wall is the only thing keeping his people safe from a brutal and unforgiving enemy. One day, Joshua stumbles across a tunnel that leads underneath the Wall. The chance to catch a glimpse...