A psychiatrist (Bernard Letrou) ventures to a remote castle to convince a brood of four vampire sisters that they are misguided, brainwashed by superstitious villagers, and not truly creatures of the supernatural. The villagers (including director Jean Rollin) confuse and abuse the sisters, before finally storming their castle. The cast descends on a hospital run by a young doctor (Jean-Loup Philippe), charged by the Queen of the Vampires (Jacqueline Sieger) to discover a cure for vampirism. This bewildering action culminates in a 'blood wedding' presided over by Sieger, in her regal hot pants, on the legendary stage of the now-defunct Theâtre du Grand Guignol.