There are two plots going on in this movie. First, a Purist group has developed a substance that can be sprayed from the air and is fatal to Newcomers. Their plan is no less than to commit genocide against the aliens. The second plot revolves around an overseer (Ahpossno) who has come to Earth to see if the aliens can be returned to slavery. George's own family is affected by the Purists hatred.
Ahpossno is his slimy sneaky self all through the movie. Matthew is the first to figure out he can't be trusted. The guy comes on to Cathy and she likes him. George becomes the second person to figure out something is wrong. Ahpossno, for his part, wants to retake all the Tectonese as slaves and make all humans slaves also.
Susan is the worst affected by Ahpossono, believing everything he says, changing their house decor and then wanting to move away from the human neighborhood.
The strong main theme through the entire series has been prejudice and how easily people came to hate the aliens. This is covered in a somewhat similar movie, District 9, which is also very well done. People don't just limit their hatred to talk; they are willing to take violent action and kill all of the aliens. This is all similar to how American Indians were hated and were targets of violence. Blacks received the type of hate but, instead of killing them, they were turned into slaves. Today the targets of hatred, least in the United States, center around those who are gay, homosexual, bisexual or transgendered with them meeting the same kind of hate and, at types, violence that those in the past met (and some blacks still do.)
The movie is good and is a strong argument against hate.
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