Twelve-year-old Caitlin lives alone with her mother — a docker at the local container port — in subsidized housing next to an airport in Seattle. Each day, while she waits to be picked up after school, Caitlin visits the local aquarium to study the fish. Gazing at the creatures within the watery depths, Caitlin accesses a shimmering universe beyond her own. When she befriends an old man at the tanks one day, who seems as enamored of the fish as she, Caitlin cracks open a dark family secret and propels her once-blissful relationship with her mother toward a precipice of terrifying consequence.