I was recently thinking about the way that the TV version of Poirot sometimes re-sets the stories in the 1920s. (Poirot stories were generally written contemporaneously, spanning the 1920s through the 1960s.) It makes sense on television for a variety of reasons—including that the 1920s were far more visually interesting than most of the decades which followed. That said, it is curious because the sorts of plots one finds change somewhat over the decades.
Nowhere is this so obvious as in the case of murder by ingenious invention. It was a common enough plot in the golden age of mysteries but seems to have fallen out of favor more recently. And a particular kind of ingenious invention has really fallen into disuse these days: the alibi by recording.
In the golden age of fiction it was a not uncommon plot that either the murder’s presence or the victim’s being alive when he was already dead was established on the basis of an overheard conversation which turned out to be a recording. (Both give the murderer an alibi, though in different ways.)
I’m curious why this has fallen out of fashion. (And of course I don’t mean that it never happens—I can think of a few TV mysteries which have employed the murderer using a recording to fake being on a stage giving a presentation when they ducked out for a minute to commit the murder. But I think that’s more properly regarded as a variant of the being-on-stage alibi rather than the recording-alibi.)
There was a certain amount of fascination with the progress of technology which one finds in the 1920s because it was an era of rapid technological progress. But our era is also one of rapid technological progress. More so, in absolute terms.
I think, though, that we’ve become exhausted with technological progress. It’s not merely that we wonder whether all the change is actually for the better—we do, but so did the people in the 1920s. In many ways more than we do, actually, since they had just come off of the horrors of the first world war and its deadly machines and poison gasses. Nuclear annihilation isn’t much of a threat any more, though technically it is still possible.
It’s also not that technology has become the realm of the specialist. It was always the realm of the specialist. It wasn’t ordinary people who invented gadgets, and it took more expensive equipment to record a phonograph in the 1920s than it does to record voice on a cell phone now.
I think it’s rather that we have a sense that life doesn’t change nearly as much as one would think it does. I don’t mean that life is mostly the same minute-by-minute. That would be ridiculous. We do far more driving and far less walking; we are constantly stimulated by electric devices and never has mediocre music been nearly as omni-present. But we remain human beings with much the same problems; our problems are just far more convenient and fast-paced.
Being so inundated by technology, we find it boring. These days (with expensive software) one could edit video to remove somebody from a security camera recording. So what? That’s not an interesting reveal. It’s really no more interesting than a mystery about wizards involving the reveal that the murderer used an invisibility spell.
What’s far more interesting in murder mysteries is the human element.
I should also note that this is probably also partially a result of short stories being mostly dead and gimmics (by which I mean clever murders) being far more the domain of short stories than they are of novels. Not that the murders in novels aren’t clever, only that they’re not generally based on one large reveal. That said, as I’ve argued in the past, structurally speaking, television murder mysteries are much closer to long short stories than they are to novels. So murder mystery short stories have generally moved to television from the written word.
And even there, recordings are not a popular alibi.