Noa lives in what remains of a Britain where floods have made the land scarce. Everyone must take an exam at 15: if you pass, you can stay in the territory; if you fail, you must go to the wetlands. Wealthy families can buy their children an upgrade to help, but norms like Noa have to rely on their own merits. Noa is a smart, funny teenage girl who is unsure about which boy she likes and is fiercely loyal to her friends. The book follows her and her friends as they face the exam. Who will pass and who will fail?.