100 years after an interstellar collision stops Earth from spinning, 15-year-old Ing discovers a metropolis hidden deep below the sea. Complete with science labs, a chapel, and a military academy, Ironhold appears to have everything she desires.
Ing's dream of joining the revered Swimmers is dashed when an incident at sea lands her in a world she could never imagine. Faced with a civilization advanced far beyond that of her decimated village on land, she is challenged in ways that thrill-and frighten.
When a fabled octopus secretly communicates with her, Ing realizes the populations of those in Ironhold and back home on land are in danger. Ultimately, with time running out, she must decide the fate of those still alive on a planet facing an imminent new peril.
Ing's search for a life other than the one prescribed by her society finds her in a realm she never imagined could exist.
