Dr Adam Royston, a scientist working at the nearby military base, thinks he knows what it is; a creature as old as the earth that slumbers for centuries, then wakes to feed on the energy and radiation produced by humans. But if he's right, and they can't find a way to destroy the creature roaming the countryside, then it's not just Buckinghamshire that could be in danger, but the whole world.
By day the village of Karnstein is a peaceful place, but by night, an unimaginable evil roams free. Villagers are found dead, their throats ripped open and bodies drained of blood. Young girls disappear and are never seen again. Rumour has it that they are taken to the castle for the pleasure of Count Karnstein, the last surviving member of the family.
Into this strange place, come beautiful identical twins Maria and Frieda. While Maria lives a blameless life, Frieda is drawn to the castle and Count Karnstein. A man rarely seen in daylight, a man steeped in Satanic ritual and the blood of beautiful young girls.
Before long Frieda and Karnstein unleash a reign of bloody terror on the villagers, and no one, it seems, is strong enough to stop them.