This film tells the story of a strange family isolated from the world. The family consists of a pair of parents, an eldest son, and two daughters. The family of five lives in a secret big house all day long. The three children have been isolated here by their father since they were young. They cannot contact people except their parents, and they know almost nothing about the world outside the high walls. After their father goes to work, they study and play in the house with their mother. All their knowledge is taught by their parents. The father tells them that the outside world is extremely dangerous, and if the children want to go out, they must wait until the "dog teeth" fall off. The father is the only one who can drive outside. He has a normal job and will bring back necessities and rewards for the children. He sometimes brings back a female employee in the company-Christian, who is hired to meet the sexual needs of his eldest son. And her several visits are quietly changing this family...