Shailene lives on an island in the middle of the ocean, surrounded by massive walls that keep out the water. That island contains the last of humanity, the survivors of the Ice, an event that froze over the entire planet. Their descendants have done well making sure the island runs smoothly and that the walls are fortified enough... or so they thought. One fateful day, the walls come crashing down, and everything Shai has ever known is swallowed by the depths of the sea. Now, her very survival depends on a sea creature she just met and the hope that nothing eats them alive.