Is this a good horror story plan?

Keep trying. It is a good start. write the whole story out first, and then go through them and take out what is not important, and add other elements. Otherwise a good start. Have you read The Shinning or Amityville Horror. Both have similar elements with the supernatural thrown in. Good stories! You need to read plenty of Horror stories to see how the writers develop their story lines. Stephen king is great with words! So are few others.