Architecture of: The Key in Alfred Hitchcock's "Notorious" [1946]

The architecture is not in the room. The architecture is in the elegantly impossible, continuous crane shot -establishing a grand party scene, floating along the landing above, down the curving & monumental stair, people coming and going, our focus at first distracted from, then invited to, searching for clues to the point of the set-up; then breezing past the usual destination (the conversation between actors) and without slowing its pace, down curiously close but never without clarity, to the tightly folded fingers of our heroine enclosing the crucial plot device of....the key.