Dirtying fingernails in sewers is fast approaching worthlessness for Zachary, a 16-year old Underworld scavenger. When footage of an Overworld girl, Rosa, is discovered, his intrigue heightens at why she expresses sadness with a lavish lifestyle. In meeting Rosa, Zachary is scorned by her opinion of the deprived. She pities him and provides a means for them to communicate. With time, friendship and something that he's never felt grows; love for another human. Knowing Rosa calls him when it suits her isn't enough; he wants to meet her, but how? Relationships in Underworld are few, let alone the impossibility with those above the ceiling. Underworld will suffer when plans to conquer Jupiter's moon, Europa move ahead. Worse is Rosa's father, a disgraced Overworld ambassador, approving the plan. Zachary must defeat the prejudice of the worlds, sneak within opposing forces, lose friends and challenge Rosa's sadness. In doing so, a twisted secret is uncovered that may devour the reason he lives; Rosa. In space, love has boundaries.