Outcast, liberator of the non-people, a mystery to herself.In a world so desperate that people trade their children for food, a girl, cast out from her city for an unknown crime becomes an unlikely hero. It is 2472. The British Isles have been transformed by climate change into a desert archipelago. The wealthy and privileged have retreated to high-tech walled cities. Those beyond the walls are known as the Non-Grata. They live a precarious, hand-to-mouth existence, surviving on the "charity" of the cities. In return, these non-people must pay a Quota, a tax paid in human life. Specifically, they give the rich something their money cannot buy: children.Isobel Twelvetrees has been put outside the walls of her city and left to die in the lethal heat for a crime she cannot remember committing. She was saved by someone or something, but when she wakes, the only companion she has is a dog with odd coloured eyes. When she learns the terrible truth about the plight of the Non Grata, she turns into a new kind of warrior. As she crosses continents with the threadbare armies of the Non Grata, in a deadly race against time to destroy the Quota and right historic wrongs, she starts to uncover the truth about herself and what she left behind.