Twelve-year old Ellie knows The Secret. She knows the truth about the Wall and the Animal Plague on Earth. But kidnapped and imprisoned on a spaceship, thousands of kilometres from home, she's unable to reach those she loves most. Or is she? As the sound in her head grows to a roar, perhaps she's more powerful than she thinks. Her twin, Mika, left in the concrete-world below, refuses to give up on his sister though the rest of her family believe her dead. When the government announces Pod Fighter, an interactive competition that becomes a national obsession, he senses a sinister connection.