Don't Look in the Basement (1973)

⁣Nurse Charlotte Beale (Rosie Holotik) is hired by Dr. Stephens (Michael Harvey) to work at a small sanitarium he runs. When Charlotte arrives, however, she learns that Stephens has died in the interim, and that she'll be taking orders from new president Dr. Masters (Anne MacAdams). Charlotte goes along, but can't help noticing how unusual Masters' approach is to treating the mentally ill. They're allowed free run of the place, and Charlotte begins to wonder if Masters isn't a patient herself.