The film shows two women achaeologists, Elvira (Gaby Fuchs) and Genevieve Bennett (Barbara Capell), who are interested in finding the grave of a famously evil vampire, Countess Wandessa. Wandessa was a medieval murderess and possible vampire. She was buried in a forest near Waldemar's Castle. They are joined by Waldemar Daninsky (Paul Naschy), a Count, who wants to get into the grave to find a holy relic, the Silver Cross and/or Silver Dagger. Waldemar we find, is a werewolf who can't control his transformations.In the process of digging up the grave, one of the girls is injured, and a tiny bit of her blood drops onto Wandessa's rotten corpse.
Genevieve gets turned into a vampire by Wandessa, and Elvira falls in love with Waldemar.
Wandessa and Waldemar eventually have a fantastic fight that takes place in an amphitheater. Waldemar sticks a cross into the one exit so that the vampire can't run away from the fight. When Wandessa finally dies, her clothes settle to the ground in a heap with her rotting corpse inside them, and maggots crawl all over her.