A Blade in the Dark (1983)
When the lights go out, the knife goes in.
Bruno is a composer trying to write a score for a horror film. Looking for some solitude in order to complete his work, Bruno rents an isolated villa in the European countryside. Unfortunately, just as he has begun to get some of his score done, he discovers the dead body of a young girl he had just met at the house. Soon, another woman is brutally murdered, and Bruno quickly becomes obsessed with finding the killer. And, when he hears what appears to be a clue on his film's soundtrack, he believes the answer to the mystery is hidden in the film he's scoring.