Would this be a rip off, even though it was unintentional?

I'm planning on a story about a school for delinquents where it eventually turns out that members of the faculty are cultists and practice blood rituals etc and are led by a necromancer who supposedly 'died' in France over two centuries ago. I knew although the basic structure of this wasn't original, but then I remembered a movie I watched once called Suspiria, about a ballet school in Germany which is staffed by witches who kill off students who start to uncover their secrets. Terribly similar but what do you think? And for some reason with witches, blood rituals and satanists mentioned in this question the suggested category was home and garden? lol?