A fascinating story of Earth-Humans on Mars. When the story opens, Mars has been colonised by Earth People for 50 years. Jim and Frank, sons of colonists, study at school for careers such as rocket pilot, areographer, planetary economist at another end of the planet, they come up against a nasty political plot to take away their colonist rights. The details of life as it might be lived are absorbingly presented-constant awareness of pressure, scarcity of water, changes in climate, vagaries of the Martian year. But the same old greed for power survives. The most thrilling and tingling kind of science fiction story, by an experienced hand -- the more exciting to young readers because it lies in the real of the unknown and unproved but distroyingly possible future. Another good bridging book.