Precipice of Sacrifice: John Mason (Legend of John Mason) by Barbara J Robertson

The story of John Mason continues with "Precipice of Sacrifice." The Rebellion has spread throughout the solar system, with brazen attacks now taking place on Earth. Maximum strength of Earth Command forces have kept Earth and Mars from being overtaken by alien and Rebel control. The losses of pilots and Space Marines are mounting, while the number of Rebels grows daily. John Mason leads the preparation of the United Republics of Earth to defend Mars and the Earth in its final conflict. But he knows the great walking reptile alien invaders - the "ONE" - want more than planetary they want humans to cross-breed, and transform into reptilian hybrids. The aliens also want John Mason as their Perfect Man. The price of victory against the aliens may be the loss of Mason’s very humanity. Will Earth Command succeed in repelling the Rebel forces, backed by the seemingly-invincible aliens? “Precipice of Sacrifice” is the third book in the successful science fiction series, Legend of John Mason.