The Secret Life of Walter Mitty (1947)

A mild-mannered pushover, Walter Mitty (Danny Kaye) longs to be free of his mundane existence, where has to contend with his pushy mother (Fay Bainter) and flighty fiancée (Ann Rutherford), among others. Indulging in elaborate daydreams, Walter finds himself on a real adventure when the lovely and enigmatic Rosalind van Hoorn (Virginia Mayo) ropes him into a situation involving valuable jewels, a little black book, and a sinister criminal named Dr. Hugo Hollingshead (Boris Karloff).