The Kessler line is named after the Kessler syndrome, collisions between space debris that leads to the formation of more small pieces of space debris in an accelerating chain reaction. It plays a key role in the story, by trapping the people of Earth on Earth. Anything that tries to pass Earth orbit is smashed to pieces by the space debris. Otherwise the book is much about the differences between the unsustainable Earth society with its damned if you do and damned if you don't laws where the environment is being destroyed and psychiatry is destroying people's brains, and a sustainable society on Mars that was founded by people who moved there before the Kessler syndrome and that is something completely different. The book also shows differences in scientific means of research between the two worlds in a way that ties into all of science's possibility of progress and the creation of a theory of quantum gravity. The story has a secret agent on Earth named Sandra Winston as a main character and focuses much on whether or not she will have time to use her illegally obtained information to save the world before it is too late.