Derek, a teenage alien guy, among a small crew of extraterrestrials in a flying saucer, has come to Earth on a "seeding" expedition where "Gargons" (the alien world''s food source animal) are to be exposed to earth in order to note their reaction to the new world''s air. If they thrive, millions more of the creatures will be brought to the planet to grow, and eventually be harvested for their flesh.