Humans no longer live on either Earth or Mars but on Jupiter now called Giant. Rings have been built in the upper atmosphere with trains running between stations built along it. Pleiti is a professor studying old Earth literature to get a comprehensive list of plants and animals that lived in certain areas of Earth before the collapse. Mossa is her former college lover now investigator that show up on her doorstep working a disappearance of a man that had connections to the university Pleiti works at. The two work together to solve the mystery and the reader gets to learn about life on Giant.

