Following a catastrophic event in 1993, the surviving population has retreated into the fortified Citadel, where they remain largely confined due to an inhospitable climate outside its walls. Joel, a bureaucrat living an unremarkable existence within this shelter, is jolted from routine when his childhood friend Grace vanishes without explanation—her unmanned vessel mysteriously arriving at the Citadel as the only clue to her fate. Compelled by the mystery and his connection to Grace, Joel abandons his comfortable life and commandeers her craft to venture into the hostile expanses beyond the Citadel's protection. As he pilots through barren landscapes and environmental hazards, he uncovers fragments of Grace's story and the truth behind her sudden disappearance.