North by Northwest (1959) remains still, one of Hitchcock's most popular films. It can be appreciated on many levels and has been called by Donald Spoto, 'a kind of poetic montage.' 

A group of spies, dealing the exportation of high U.S. government secrets, is headed by Phillip Vandamm (played by James Mason). Their target is Roger O. Thornhill (Cary Grant), whom they mistake for "George Kaplan," a decoy created by the CIA.

Thornhill becomes involved in a bizarre web of circumstance evidence, that includes an affair with Eve Kendall (Eva Maria Saint) mistress of Vandamm and a secret agent. The journey takes them from New York to North Dakota and includes the famous sequence of 'the chase in the cornfield' and the flight over the surface of Mt Rushmore.

'Hitchcock has called this film the summation of his American period.  He might have suggested, more accurately, that it summarizes the espionage thrillers of his entire career.'

Spoto, Donald. The Art of Alfred Hitchcock: fifty years of his motion pictures. Doubleday, 1976, pp.339-353.