The morning after the sky fell, Mary Solomon washes ashore alive — and something washes ashore with her, living behind her heart.
While her father's man Guthrie descends into the burning city with a satellite phone and an impossible errand, Mary learns what the deep left inside her: a wound that heals like sapphire, a voice that speaks in waves, and a shape that stands up out of her when she stops fighting. In the ruins she finds new company — Tia, Logan, and a young man named Zach with a steel case he claims is the reason he's alive — and one thin bar of signal that changes everything: the shielded city of Sangara is still standing.