The Air We Were Made For

Romy Hume has spent nine years buying her little brother's next breath by the hour. In the mountain city of Sennet, an ancient machine scrubs the planet's poisonous air, and a single test at seventeen decides who breathes easy and who suffocates slowly. Then Romy's test runs nineteen minutes on raw air and doesn't stop. A frightened physiologist alters her score, hands her three rules, and sets her on the trail of a lie four hundred years old — and a machine that is already dying.