Two young brothers, Prosper, age 12, and Bo, age 5, were recently orphaned when their mother died.  Her sister, their aunt, wished to adopt Bo but not Prosper, causing the two boys to run away for fear of being separated.  They venture to Venice, having heard so much about the city from their mother prior to her death.  Once they arrive, they meet a group of other boys without homes who live in an old abandoned theater.  The leader of the group, Thief Lord, claims to steal from every wealthy family in the neighborhood, and gives what he steals to the others to sell.  Eventually, it is revealed that Thief Lord is actually from a wealthy family, and the boys’ aunt continues to chase them, despite their having run away.