Deep beneath a moonlit sea, a small lanternfish named Sable has spent her whole life lighting the way for others — never once stopping to look up and wonder what lies beyond the water's surface. When a shipwrecked music box drifts down to the ocean floor, its half-remembered lullaby awakens in Sable a question she never knew she was allowed to ask: what is the sky? A glowing underwater fable about curiosity, the courage to look upward, and the unexpected places where we find we belong.