Something evil has taken possession of the small town of Santa Mira, California. Hysterical people accuse their loved ones of being emotionless impostors; of not being themselves. At first, Dr. Miles Bennell (Kevin McCarthy) tries to convince them they're wrong...but they're not. Plant-like extraterrestrials have invaded Earth, replicating the villagers in giant seed "pods" and taking possession of their souls while they sleep.