Two years ago, a wormhole opened and ushered vicious dragons into the world. The dragons burned Earth's cities to the ground and sent its inhabitants scattering for cover--and since then, Ayanna Grace, a seventeen-year-old Black girl, has been scratching out a life in an abandoned subway system, part of an extensive underground community. Underground, medicine runs short and outbreaks of disease spread uncontrollably. The water supply is low, uprisings occur frequently, and dragon attacks are imminent. But those aren't the only challenges Ayanna is facing: she's also busy wrestling with her feelings, torn between Richard, who she's known all her life, and Jackson, a mysterious newcomer. Worse, her mentor, the community's only doctor, is dying from a failing heart. With no hope of rescue from aboveground, will Ayanna be able to save him before it's too late?