John Shaw just wanted to go fishing and live off the land—now he is one of only a few survivors involved in a horrific crash between a locomotive and a flying saucer. Stranded in an unforgiving environment, desperate to survive, he and the remaining passengers must outrun, and outsmart, the alien life forms that are picking them off one by one. The clash between man and invader intensifies, and the end of the human race looms near.