Urchin (2007)

In a tunnel deep under Manhattan, the Old Man rules the citizens of Scum-City. He swears to lead them to a paradise within the hollow earth once he finds five noble souls; but until then his followers must steal and deal to support him. A terminally ill hunchback named Goliath, crazed by his approaching death, decides to find the five noble souls and present them to the Old Man;by beheading New Yorkers he deems worthy of the honor. Meanwhile, another Scum-City dweller known as The Kid tries to do the Old Man's bidding, tangling with deadly gangsters and eccentric drug dealers-even though The Kid is only nine and his main weapon is a water pistol filled with acid. As both Goliath and The Kid pursue paths they believe will lead to paradise, they rob, kill;and inevitably confront each other in a grand showdown.