When six-year-old Marissa loses her mother, she is taken by her father to live on a small Thai island in the Andaman Sea. There, she forms a deep friendship with Arielle and together they explore the fragile wonders of its forests, reefs, and beaches. Holding their breath for minutes at a time, they learn to dive into the deep, as effortlessly synchronized as the manta rays they come to know by name. Then, on Boxing Day 2004, when the Indian Ocean tsunami makes landfall, they are swept up by the first wave and separated.

Eight years later, Marissa is living in New York. She spends her days wandering through the city and her nights seeking solace in the beds of strangers. As the city prepares for a devastating storm, Marissa reflects on her past and learns how to sustain herself in a precarious world.