Synopsis: The conflict between man and nature was never more unconditional than on the planet Dextra where the DNA that determined all life runs in reverse from Earth - and where no compromise can exist. Either the green of Terra must exterminate the purple of Dextra or be exterminated. Yet truce lines were eventually drawn, time did pass, colonies and their governments did arise that seemed stable... but the time had to come when the battle would lead to Armageddon. When it came it caught the humans in internal warfare, it caught the Dextran world developing a biological super-weapon, and found two humans confronting both crises together. (from the back cover of the first edition)