Color Out of Space

It does fall short with the family. That would be where the story's real genius would occur but like you said, that's sort of a recurring theme with Lovecraft. I get the impression from films based on his stories (and just by reputation) that he likes pulling monsters, demons etc. out of thin air. The family's probably just a pretense to show the creature.

The family's all but doomed the moment they come into contact with some form of water. I can't remember if Cage was affected by this point but by the time he first got aggressive with his daughter, he was full blown contaminated. The daughter's witchcraft came up again because she carved something in herself and it showed through a montage that the shape of her cut was the same shape of some citadel or tower on the planet where the organism came from. At least I think that's what happened. I think her rebellious, teenage angst witchcraft might have enabled the apocalypse. But I also think the witchcraft bid at the beginning foreshadowed the water as a problem and set up the tension between the family and the mayor, since the mayor also has it out for Cage for not selling her his share of the land.

I like the idea, insanity, fragility of the human mind. I'm not always in the mood for that type of story, so I guess this film struck my brain while the iron was hot.