The theme of this story is pushing the Envelope. This phase was used a lot in the book. This means to attempt to extend the current limits of performance and to go beyond commonly expected boundaries. This theme is show in the book by many examples like Chuck Yeager breaking the speed of sound. People going to space and orbited the earth these where all known to be impossible during that time. These examples supports the theme as it shows how people went beyond the expected boundaries and made new records. The author uses many more examples like these to tell us what the theme is.  This book is about Pilot who break different record, pilots who became astronauts for the USA. It is about their life. It talks about the mercury mission and about what happened in this mission.