Five prominent biophysicists give the United States government an urgent warning: sterilzation procedures for returning space probes may be inadequate to guarantee uncontaminated re-entry to the atmosphere. Two years later, Project Scoop sends seventeen satellites into the fringes of space in order to 'collect organisms and dust of study'. Then a probe falls to the earth, landing in a desolate area of northeastern Arizona. A little while later, in the nearby town of Piedmont, bodies are discovered heaped and flung across the ground, faces locked in frozen surprise. The terror has begun...