A group of Parisians arrives in a rural area to cure four sisters from their madness; the sisters who are living in an old castle believe they are vampires. One sister doesn't like to go out in the sun. Another sister thinks she is blind. But Thomas, one of the Parisians who is a psychoanalyst, doesn't think vampire legends are real. He wants to find a way to get close to them and convince them that they are not vampires. However, Thomas is unaware that there's a strange man who is manipulating the sisters, and that there is a malevolent force in the forest.