In an interview with François Truffaut, the principal user of this term explained that this kind of thing was actually "nothing at all" by citing the example of Cary (*)  
The biographer Donald Spoto credits the screenwriter Angus MacPhail with coining this term, which has been used to describe a song memorized by the elderly Miss Froy and a phrase muttered by "Mr. Memory". In an interview with François Truffaut, the principal user of this term explained that this kind of thing was actually "nothing at all" by citing the example of Cary (*)  Grant's character Roger trying to get one of these things from a counterintelligence agent. The military secrets in  The 39 Steps , James Mason's actual plan in  North by Northwest , and the title statuette in  The Maltese Falcon  are examples of, for 10 points, what plot devices that take the form of goals or objects sought by the protagonists of films, whose Scottish name was popularized by Alfred Hitchcock?
The biographer Donald Spoto credits the screenwriter Angus MacPhail with coining this term, which has been used to describe a song memorized by the elderly Miss Froy and a phrase muttered by "Mr. Memory".
MacGuffin s [prompt on  plot device s]