aul Marnac (Paul Naschy) and his infirm wife Geneviève (Julia Saly) move to his childhood estate in the French countryside. The estate is also the site of the castle inhabited by Paul's ancestor Alaric de Marnac, who was known for brutally slaughtering anyone whom he suspected of infidelity. There is a legend that Alaric rises from the grave to continue his deeds. The estate is currently inhabited by Paul's aunt Maville (Lola Gaos) and cousin Julie (Frances Ondiviela, billed as Pat Ondiviela). Right after Paul and Geneviève arrive, mysterious things begin to happen. Geneviève begins to wonder if the legend about Alaric is true.

Overview from themoviedb.org