I really enjoyed this, the art, the sound, the atmosphere, everything!
I basically solved it without resorting to hints, which is to say, I figured out what had happened. But I couldn't figure out the right combination of words in the blanks to solve the puzzle, until I looked at the hints. I am glad I did, because my mistake was that I did not think that "passkey" referred to a physical object!
Maybe it should have been obvious, I know they weren't using digital encryption in 1934, I guess I was just primed by reading "password" and thinking "passkey" was just a term the alarm company used to sound more secure.