The Mcguffin is an irrelevant object (nothing at all), around which the action is structured
Certain function of certain object
McGuffin signifies only that it signifies
They signify the signification as such, but the actual content is insignificant.
39 Steps: plans for airplane machine (we never see the airoplane)
Foreign Correspondent:
secret clause in a defense treaty, so secret that it had to be memorized by those present. It could not even be put on paper; an ideal signifier beyond writing.
Lady Vanishes:
The tune
NBNW: the microfilm
