Night Monster

Dr. Harper is a psychologist. Ingston Mansion is a terrible place with a bad reputation. Harper is invited to judge the sanity of Margaret Ingston. She is disturbed, but is it insanity? Dick Baldwin appears on the scene. He's angry at the threats he's been getting from somebody at Ingston Mansion. There are three more doctors at the house too and one by one they are murdered. Who is the killer?