The book opens with a short section providing backstory. As part of the first mission to Mars, a team of astronauts exits their spacecraft for the first time, only to see another man standing there, connected to an air hose that leads through a wormhole to a laboratory in California. The wormhole generator's inventors, Nigel Sheldon and Ozzie Isaacs, chose to test it by beating the crew, by moments, to become the first humans to reach Mars. The saga then moves into the Commonwealth era in 2380, when humanity has used the wormhole technology to colonise several hundred planets across hundreds of light years.