A man suffers from the curse of lycanthropy and seeks out the aid of a German doctor and his wife who are experts in the occult. Unknowingly, the cursed man has summoned two vampires instead, who have sinister plans of their own for the werewolf.—Humberto Amador
Rudolph Weissmann [Manuel Manzaneque] and Countess Janice von Aarenberg [Dyanik Zurakowska]are engaged, and their fathers are throwing a masked ball in their honor. They've beenfriends and lovers since childhood but, when "His Satanic Majesty"Waldemar Daninksy [Paul Naschy] dances with her, Janice falls instantly in love. Thenext day, when she stops at an antique shop to pick up a vase she ordered,the shopowner formally introduces Janice and Waldemar. Shortly thereafter,Janice runs into Waldemar again when she stops to bless herself withholywater at church. Later, as Rudolph and Janice are driving, they stopat the old, abandoned castle and, lo and behold, Waldemar is there, too,"for the peace and solitude," he says.
Waldemar explains to them the legend of the castle. It was built bythe Wolfsteins of Poland. Imre Wolfstein is said to have been bitten by awerewolf and became a werewolf himself. A silver cross was driven throughhis heart, and he was buried in the tomb in the castle. Legend has it thata werewolf can only be killed by a silver bullet shot into his heart byone who loves him. Therefore, Imre isn't really dead. Janice is intriguedby the story, but Rudolph is peeved at Janice for talking to Daninsky, whohas a reputation for being an oddball.
A storm is approaching. On his way back to town, Waldemar stops tohelp two gypsies, Gyogyo [Gualberto Galban] and Nascha [Rosanna Yanni], push their wagon out of the mud. Whenthey ask if there is someplace nearby where they can take shelter from thecoming storm, Waldemar suggests the castle. After having a bit too muchwine, the gypsies explore the castle, coming upon the family crypt wherelay the tombs of the dead Wolfsteins. Thinking the dead may be buried withjewels, they begin opening the tombs. A ring and a necklace later, theycome upon the tomb of Imre Wolfstein. When Nascha pulls the silver crossfrom Imre's chest, Imre reawakens and tears them both apart.
The next day, two villagers are found dead. It looks like they'vebeen torn up by wolves, so the rest of the villagers form a party to huntthem down. During the hunt, Rudolph is attacked by Imre. When Waldemarjumps in to help, he is bitten by the werewolf just as he plunges thesilver cross back into Imre's heart. Out of gratitude for Waldemar havingsaved his life, Rudolph promises to shelter Waldemar and help find a curefor his condition. Hoping to spare Janice from knowing about him, Waldemarsends her a message to tell her that she must forget him, but Janice isn'tput off that easily. She follows Rudolph to the castle where she finds heis keeping Waldemar locked behind bars. Rudolph and Waldemar explaineverything to her, and Janice agrees to help them. While rummaging throughthe library, Janice finds a letter to Imre Wolfstein from Dr JanosMikhelov dated 1929. In the letter, the doctor intimates that he may havediscovered a cure. Rudolph suggests that they contact Mikhelov to see ifhe can help.
Dr Mikhelov has since passed away, but his son Janos [Julián Ugarte], who has takenup his father's research, arrives at the train station, accompanied by hiswife Wandessa [Aurora de Alba]. However, instead of helping Waldemar, Mikelov and his wife,who are vampires, cause Waldemar's body to become possessed by Satan, andthey hold him in chains while they feast on Rudolph and Janice, puttingthem under their power, too. They even manage to pull the silver crossfrom Imre's heart and bring him back to life, only to keep him chained upnext to Waldemar (although Waldemar kills Imre one night when they bothmanage to break loose of their chains).
Rudolph and Janice's fathers are becoming increasingly worried overthe strange behavior their children have lately been showing --disobedience, wandering about at night, seemingly entranced, etc.. WhenRudolph leaves a letter with his father asking for help and Janice's dadfinds silver bullets in her bedroom, the dads decide they must takeaction. They go to the castle, where they hear groaning coming from thecellar. There, they find Waldemar in a cage and release him. When theynotice the red pentacle (the mark of the wolfman) on his chest, Waldemarexplains how he was bitten by the werewolf and advises them to loadJanice's silver bullets into their guns.
Then they all go off to look for Janice, Rudolph, and the vampires.When they come upon the vampires' coffins, Waldemar plunges a stakethrough Wandessa's heart, thus releasing Rudolph from her bondage. Beforethey can destroy Janos Mikelov, however, Waldemar begins to change intohis werewolf self. Janos escapes with Janice. When Waldemar's change iscomplete, he catches up with them. Waldemar and Janos struggle as Janice,Rudolph, and the dads watch. Janos is suddenly consumed by fire (thatsprings up out of nowhere!), releasing Janice from his spell. As Waldemarturns on the dads and Rudolph, Janice grabs the gun from her father andshoots four silver bullets into Waldemar. She then rushes to Waldemar'sside as he turns back into his human form and dies. Rudolph leads her away.[Original Synopsis by bj_kuehl.]
