"Joes Palace" was the prequel to this fine movie.

I feel although this movie was much better that Joes Palace, it does give some insight on the house, and the owner of the house. Capturing Mary was more intriguing, but the ending to the first movie can give you a sense of what horrific stories Greville told Mary in the cellar.
I watched both. Maggie Smith is fabulous, and seeing Ruth play Mary was perfect. I know her from Showtimes, The Affair, which is also fabulous.