Fast, witty dialogue is a defining virtue of The Lady Vanishes (1938; dir. Alfred Hitchcock). Although it's a mystery film, with people under various forms of menace, and though it includes gunfire, kidnapping, and murder, it's also quite humorous. Dialogue is one source of humor. Stereotyped characters are another. The stereotypes are mainly ethnic: British, Italian, German, and perhaps East European—I wasn't certain about the last. Most of the film takes place on a train, and among the various passengers are a man and woman who've had an affair, two British gentleman traveling to a cricket match, a doctor, a countess, an Italian magician, a dowdy middle-aged woman (who disappears), and various others. Some humor comes from people of one nationality not being able to understand the language of another.
A young woman traveling to meet her fiancé shares a compartment with a middle-aged woman. When the older woman disappears, the younger woman takes it upon herself to find out what happened. No one believes her that the woman has vanished. In fact, no one claims to remember having seen the woman at all. As the young woman’s investigation develops, the mystery deepens, and so on.
The story reflects the crisis in Europe as political affairs in Germany and Italy continue to worsen—although neither is mentioned, Hitler and Mussolini are in power, and the prospect of war is in the atmosphere of the film.
Hitchcock’s fascination with human faces, with an array of often eccentric and funny characters, plays into the humor of the film.
Portions of the film, especially early scenes, are fairly risqué for the time. There are also elements that are difficult to interpret, given the year the film was made and the year in which I watched it. In one scene, the two cricket fans are forced to share a single bed while waylaid in a hotel in the Alps: we see them in bed together, in what I have to say is a cuddled-up position: one of the men has his shirt off. The other, when he gets out of bed to answer the door, is wearing a nightshirt and no pajama pants. In 2016 we'd conclude the two men are gay, but I suspect that in 1938 most audience members (except perhaps gay audience members) would not have thought much of it, other than to find it humorous.