In the 1978 sci-fi horror film 'Invasion of the Body Snatchers', San Francisco becomes the target of an alien invasion. The extraterrestrial entities replicate and replace human beings while they sleep, leading to a city filled with emotionless duplicates.
Kaufman's remake made 70s paranoia literal: everyone you love replaced by a smiling copy, capped by one of the bleakest final shrieks in the genre.
One by one the city's people are replaced by placid duplicates, until the only humans left are the ones still screaming. Everyone you trust has already changed.