Hello.  I remember watching an old movie on TCM.  I think it was black and white.  It was described as being a movie made up of B actors, but I’m not sure if I’m remembering that correctly.  Anyway, from what I can remember, the movie stars a nurse (I think) that was kidnapped and set up in an opulent home/mansion.  She was told she was the heirs wife (I think).  She knows she’s not, but they’re trying to convince her she’s mad or has forgotten. There’s the “mother-in-law” that’s a part of the “they”.  At one point, she tries to send a letter, and there was a tense scene of her trying to get the letter out of the home and sent.  If anyone can tell me the title, I’d much appreciate it.