Fascinating start
This is a wonderful submission with a lot of potential. You have the possible vampire motif with the master sleeping downstairs. The potential danger to the boy who disappears at the entrance connecting to the later screams. A variety of ghosts and stories that can come from them. And you have the heroine.
I see three possible directions from here.
Heroine: The bishop sends her to be servant but secretly hopes she has the power to clean up the mess. Exactly what powers she has is up to you.
Possession: She is possessed by the red lady who was the master's old paramour. The evil acts afterwards could be quite spooky. After she fights of or is released from the possession, the acts she performed could drive her to her own suicide and continuation in the house as just another ghost.
Anti-heroine: Possession, meeting the master, destroying the master and becoming the new "lady" of the house.
The boy could fit in as cowardly assistant, endagered victim, sacrifice that motivates her to act, or actual victim (hers or the master's). I look forward to seeing where it goes.
I never know how to mark interactivity or humor on a submission like this so forgive the 0s, please. Overall I give it a 9 because it is incomplete but I think it will be a 10 when it is finished. The sound at this time has no dynamics since it is still in the buildup phase. Keep dynamics in mind and I think sound will go up too.
Excellent work.