At the core of the film lie questions of identity in a larger sense – questions which rapidly precipitate around issues of gender.  Herrmann’s lush score speaks first to the notion of Marnie’s broader muddled identity in his themes for her.  His Marnie-in-action theme, which surfaces during her appearances “in character” at the beginning of the film, is marked by a compound meter – one which imposes a second meter over a primary meter in much the same way as Marnie imposes her contrived personae over her true identity.  As Marnie resolves her true identity and drops her guises, the compound meter subtly gives way to a simple one.1

Compound rhythm; this clip from the overture in the title sequence

These identity issues are hardly new to Hitchcock’s work: from Vertigo’s Madeline (and Scotty, for that matter) to Psycho’s Norman to North By Northwest’s Roger, Hitchcock consistently toys with notions of ambiguous and multiple identities, especially in the realm of gender norms.  In Marnie, though, Hitchcock looks the issue square in the face: finally, he dedicates a whole film directly to the process of unearthing his protagonist’s identity.