Since people seem to be recommending things, I recommend the movie
   "Sebastian".   Dirk Bogarde, Susannah York.
   [1]https://www.youtube.com/watch?v=bIK3OYnD9MY
   Out of date even when it was made, I think it really represents the
   cryptography situation as of the 1930's.
         Jim Bell

References

   1. https://www.youtube.com/watch?v=bIK3OYnD9MY