Six thousand metres below the surface of the Atlantic Ocean, suspended above an abyssal plain by a cable lattice and the collective stubbornness of eleven international research institutions, Station Hadal rotates slowly in darkness.

The station is not large. Six researchers. Four months per rotation. A cylinder of pressurised air and recycled water and fluorescent light, surrounded on all sides by cold that would kill a person in four minutes and pressure that would close a submarine like a fist.

They come to study the deep. Specifically, they come to study the creatures that live in it—organisms adapted to conditions that should be impossible, that have survived every mass extinction since the Cambrian, that have continued their slow commerce in the dark while continents moved overhead and species rose and fell like tides.

The station's logs are called Letters—a tradition started by the first crew, who noted that by the time any message reached the surface, enough had changed that it felt like correspondence rather than communication. You write down what you found. Months later, someone reads it. The gap between is the deep itself.

Dr. Mira Osei has written more Letters than anyone in the station's history. She is working on an answer to a question she has not yet learned how to ask.

This is what the Letters say.