After decades of Air Wars, gravity divisions, and hazardous pollution levels, Earth's vegetation has nearly been obliterated. New Urbanite, the last surviving city, was assembled out of the resulting havoc.

Sparrow is one of many vessels implanted with an oxygen-producing plant used to keep this cobbled-together metropolis afloat. But her imaginings of unfamiliar worlds and wild adventures grow beyond the facility she's lived in all her life.

Fulcrum is a rocketeer who lives with his family in the poor, polluted fringes of New Urbanite. He is tasked with the routine job of disposing of a mysterious metal crate, only to discover Sparrow strapped inside the copper confines. Realizing the dangerous secret she holds, Fulcrum faces an impossible choice-one that could cost him everything.

In a city starved for air, what will he do with a girl who emanates oxygen?