Given the question: Build a movie plot around this: What did the fireworks display accidentally explode? Some ammunitions lost at the site in WWII
The answer is:
Set in the modern day at a European estate, Carmilla is torn emotionally by the engagement of her friend Georgia to her cousin Leopoldo. It is hard to tell for whom she has the strongest unrequited emotions. During the masquerade ball celebrating the upcoming marriage, a fireworks display accidentally explodes some munitions lost at the site in WWII, disturbing an ancestral catacomb. Carmilla wearing the dress of her legendary vampire ancestor wanders into the ruins, where the tomb of the ancestor opens slowly. Carmilla returns to Leopoldo's estate as the last guests depart. Over next few days she proceeds to act as though possessed by the spirit of the vampire and a series of vampiric killings terrorize the estate.