In this biblical action-adventure, set during the waning years of the Roman Empire, Fabiola, the beautiful daughter of a wealthy patrician, falls in love with a Christian slave, Vibio.

Plant-like extraterrestrials have invaded Santa Mira, a small town in California, replicating the villagers in giant seed "pods" and taking possession of their souls while they sleep. In a terrifying race for his life, Dr. Bennell escapes to warn the world of the deadly invasion of the pod people.