In the cellar of the local cursed castle, Satanists are cutting out the hearts and drinking the blood of virgins in order to keep alive their Great Mistress Isabella Isabella Drupel [Rita Calderoni], a witch/vampire who was staked through the chest and burned to death in the 14th century. They currently await "the 25th moon", when Isabella (chained to a wall and with a big hole in her chest) will be able to fully reincarnate in another body. Neither the stories about the castle being the site of the Inquisition, nor the heartless village virgins being found all over, nor the fact that some odd occultist [Raoul Lovecchio] and his servant are also living in the castle, phases Jack Nelson [Mickey Hargitay], the castle's new owner. In fact, one of the first things Jack does is to throw an engagement party for niece Laureen [Rita Calderoni] who is marrying a local boy, Richard Brenton [William Darni].
Jack doesn't care about the castle's notoriety because he is actually Count Dracula, and he's been waiting 500 years for the day when his beloved Isabella will return to him. He doesn't care about the occultist either, because it was he who helped remove Isabella's body from the stake all those years ago. In fact, many of the male guests are also vampires who have been awaiting Isabella's return, and most of the female guests are reincarnations of the same girls who were shouting "Burn the witch!" all those years ago when Isabella was suffering.
[Herein insert a good 45 minutes of scenes with no continuity and even less sense, mostly of Isabella being staked and burned, the virgins being seduced by the vampires, Christa [Christa Barrymore] being buried alive and then returning as a vampire, lots of bare breasts and women being held by the torturers, and Laureen escaping from a tightening cage of knives and falling into amnesia about what happened to her.] This kind of stuff goes on until Richard stumbles upon one of the occultist's books that explains how Vampires need blood uncontaminated by semen (i.e., from virgins) and Jack and the occultist explain how everyone there has paid a role, past and present, in Isabella's death.
It is the night of the 25th moon. All the vampires suddenly go on a feeding frenzy. Two of their victims escape but, while they are running through the valley clothed only in a black cape, a lightning bolt strikes a wooden cross and sets it on fire. The villagers see the cross burning and, like in the old days, start screaming there be witches here. The villagers attempt to kill the girls, but the occultist suggests that they be allowed to pass the altar at the crossroads where it is said no demon can pass without being incinerated. The villagers agree, and the two girls are promptly engulfed by fire and disappear, reappearing in the castle cellar where they rejoin the other girls being held as sacrifices to Isabella. Tired of all the mysteries and disappearing girls, Richard confronts the occultist who delivers the moral of the story: There is a thin line between the known and the unknown, the real and the unreal, and maybe the things we see are just the things we want to see. Profound?
Meanwhile, Laureen has disappeared again. She has become the Chosen One, the one who will provide the eyes and ears of the reincarnated Isabella. Only Laureen must be a willing body donor. In a drugged state, it looks like Laureen is going to consent, but just as Isabella begins to awaken, Laureen cries out "Monster!" and the spell is broken. Laureen then kills Jack, and the next thing we know, Laureen is waking up in her own little bed oblivious to it all.