On the night of a comet storm, young David Gardner (Hunter Carson) sees an alien spacecraft land in a sand quarry behind his house. This is the beginning of an alien invasion that sees David's...

On the night of a comet storm, young David Gardner (Hunter Carson) sees an alien spacecraft land in a sand quarry behind his house. This is the beginning of an alien invasion that sees David's parents George (Timothy Bottoms) and Ellen (Laraine Newman), his teachers and the townspeople slowly assimilated by the alien lifeforms. The only one who believes David is the school nurse (Karen Black). Together, the two enlist the aid of the U.S. Marines to help save the world.