The Fifth story in the 'Space Rebel' series for Young Adults especially. When Commanders Jim Atkins and Ali Mukbar have the chance to join a Scientific Expedition to the distant Extar System where two Comets are due to impact a planet. No one expected to encounter dangerous Life-forms there. Kharloriasn Biologists had thought the System too young for these to have developed. But even more deadly than those were the Warriors of Canergorm, temporary allies of the Dagar Confederation at war with the Kharlorian Empire. At first it was a Contract to take some Dagar scientists to study the Comet Impact. But finding Ali and Jim were going, Ja Dagar promised further payment for eliminating Ali and Jim. When the Canergorms immobilised all the Kharlorian Saucers and captured Ali and others including Princess Clyra Vergred, they hoped to getr still more. With Jim and just a few scientists still free they are their only hope.