After escaping the clutches of Mayor Highshine for a second time, Scrap, Paige and Gnat make the perilous journey to the ocean jungles in search of the last rocket ship on Somewhere 513. But as they struggle to liberate the ship from a family of vicious frogbears, disaster strikes and it suffers a near-fatal crash.

As Scrap works to repair the ship, things go from bad to worse when he makes a discovery that means leaving is impossible. But with the forces of Mayor Highshine closing in, staying isn't an option either. As old rivalries return and new alliances form in the midst of a final stand-off, Paige faces an agonising decision if she is to keep her promise to her mum to keep Gnat safe...