Synopsis: Earth had been destroyed, but man had built his colonies on Mars and Venus and the far-flung moons of Jupiter and Saturn. Mutation and forced breeding had changed these people so they were no longer human. Clyde Lester, the last man on Earth, had a special problem. From somewhere in space there originated strange radio signals which could only come from beyond the orbit of Pluto, the outermost planet. -- quoted from this book's product page on Amazon.com as of 2017-02-17.