Invasion of the Body Snatchers are an American science-fiction horror films. The film's storyline concerns an extraterrestrial invasion. Alien plant spores have fallen from space and grown into large seed pods, each one capable of producing a visually identical copy of a human. As each pod reaches full development, it assimilates the physical traits, memories, and personalities of each sleeping person placed near it until only the replacement is left; these duplicates, however, are devoid of all human emotion. Little by little, a local doctor uncovers this "quiet" invasion and attempts to stop it.