The Forbidden Room.

Fulfilling a promise made to his mother on her deathbed, Dr. James Gibson finds his sister Pauline who has run away after giving birth to an illegitimate child. His sister's mind has snapped and Gibson takes his sister and his baby niece home with him. The years pass and the niece has grown into a beautiful woman, while her mother is kept locked in a room that the young woman is forbidden to enter. Gibson and his wealthy neighbor, John Morris, are both interested in hypnotism, and one night the two men conduct an experiment by hypnotizing Gibson's niece. This film is presumed lost.