The story follows a family group of inbreeds who've been suffering with a hereditary disorder known as'Merrye syndrome', named after the household in which the disorder developed. This malady causes its sufferers to go into a condition of age regression that continues throughout the rest of the person's life, making them along with a child's wisdom and also starts at age ten. The last generation of their household has been entrusted to the care of the family chauffeur (Lon Chaney Jr), and it is well for those odd people until a greedy division of their family determines that they would like to alleviate the category of its house. Mental disease has always, and can be, a thing for horror movies since it probes into the unknown and Spider Baby makes use of the truth.