Noa lives in what's left of a Britain where flooding means land is scarce.

Everyone must sit an exam at 15: if you pass you can stay in the Territory, if you fail you must go to the Wetlands.

Rich families can buy their children an upgrade to help, but 'Norms' like Noa must succeed on their own merits.

Noa is a bright funny teenager, not sure which boy she likes, devoted to her friends.

The book follows her as she and her friends face the exam.

Who will pass and who will fail?