Puck, expelled from yet another boarding school, is on her way back to her parents, who are doing alien research on Shoon.  She's worried because she hasn't seen them in years and now she's in trouble. On board The Cat's Cradle, Puck befriends Hush, a native Shoowa, who is also returning to his home in shame.  He was entrusted with a symbol of freedom for his people, and now that treasure has been stolen.  He believes the Soo is hidden somewhere on The Cat's Cradle, and he must recover it before they reach Shoon and before it can be smuggled off the ship.  Puck is determined to help, even though it means putting her life in danger--danger from the crew, other passengers, and the ghosts who are haunting the ship.  If she fails, neither she nor Hush can return home with dignity.