For the filmmaker and drama writing theorist Yves Lavandier, in the strictly Hitchcockian sense, a MacGuffin is a secret that motivates the villains.[20] North by Northwest's supposed MacGuffin[21] is nothing that motivates the protagonist; Roger Thornhill's objective is to extricate himself from the predicament that the mistaken identity has created, and what matters to Vandamm and the Central Intelligence Agency is of little importance to Thornhill. A similar lack of motivating power applies to the alleged MacGuffins of the 1930s films The Lady Vanishes, The 39 Steps, and Foreign Correspondent.