The Unbreakable Discussion on Impossible Alibis

 

Every few years, the topic of alibis and impossible crimes is brought up, "But is it a Locked Room Mystery?," "Impossible Crime and Alibi's" and "On A Defense of the Impossible Alibi Problem and "Doylist" Impossibilities," which were fruitless attempts to try and nail down what constitutes an impossible alibi – everyone had their own ideas and definitions. The line separating a regular, unbreakable alibi from an impossible one remained vague and undefined. So a consensus on the subject was never reached and to outsiders it must have looked like discussions on the detective story's equivalent of Big Foot or UFOs.

The question of impossible alibis was raised again following my review Christianna Brand's Tour de Force (1955) back in November. Tour de Force is a strong fan favorite and the new British Library edition won the 2024 Reprint of the Year. I personally think Brand's London Particular (1952) is more deserving, but Tour de Force is nonetheless a plot-technical marvel in how it constructs and then rips through half a dozen alibis. So understand why the book has its fans, but Brand has written better and disagreed that the alibis amounted to an impossible problem. I tried to explain why they weren't impossible alibis, but my arguments were scoffed at and rejected in the comments. What can you do?

I promised to return to the subject in the new year and dedicate a post to it. I'm not disillusion enough to think this is going to settle the issue, but at least it will give something to refer back to when it's brought up again in the future.

I always thought I had come up with a very easy, crystal clear way to distinguish between an ordinary, manufactured alibi and an impossible alibi – a difference depending on a tiny, devilish detail. An ordinary, non-impossible alibi is created with fabricated or misleading evidence like manipulated clocks, witnesses or paperwork (e.g. train or movie tickets). So an ordinary, non-impossible alibi involves retracing the steps of the murderer/suspects and not uncommonly involves breaking down one, or more, identities which is commonly associated with the Realist School of the Golden Age detective story. Mike Grost writes on his website "faked alibis and misleading trails often turn on a breakdown of identity" with "what seems to be a trail left by two, can really be the work of one" or "one person's trail can really have been left by two people" ("there are many complex variations on this..."). Mystery writers like Christopher Bush and Freeman Wills Crofts made their name with rigging up and tearing down such sort of alibis, but no fair minded person would seriously consider them a variation on the impossible crime. But when does it become one?

An impossible alibi, in my opinion, entirely relies on the murderer appearing to have been physically incapable of having carried out the deed. Not because the murderer claimed to have been somewhere else, but because their was a hard, physical limitation on the murderer's freedom to move or act. For example, the murderer was imprisoned or undergoing surgery at the time of the murder or a physical handicap apparently keeping them from off the list of suspects. Like a wheelchair bound murderer with the victim lying on the first-floor landing or one-armed killer who found a way to break someone's neck. So the apparent physical restraints alibi the murderer. Not clocks, witnesses or train tickets. The TV series Monk had a couple of the best, modern-day examples of the impossible alibi (e.g. Mr. Monk and the Sleeping Suspect, 2003). This distinction is not merely a personal, arbitrary one, but has some reasoning behind it.

The locked room mystery/impossible crime and the unbreakable/impossible alibi are both subcategories of the good, old-fashioned howdunit in which the focus is not on who committed the crime or why, but how it was done – which today are more commonly referred to as "perfect crime" stories. At it's most basic, the howdunit concerns a puzzling murder method or very thorough disappearances. Two classic examples include Dorothy L. Sayers' Unnatural Death (1927) and Crofts' The Hog's Back Mystery (1933) in addition to the works of R. Austin Freeman and John Rhode. The unbreakable alibi and impossible crime distinguished themselves from the regular howdunit by giving the murderer a seemingly incontestable alibi or make their crimes appear like a complete impossibility. A body inside a tightly locked or guarded room. A lonely trail of footprints ending in the middle of a field of unbroken snow. A ten-ton statue impossibly vanishing within the blink of an eye. You know the variations and they're immediately recognizable to everyone who can tell the difference between a closed circle and locked room.

So assumed applying the same principle of having to present an apparently physical impossibility, in order to weed out the garden variety alibis, made for an easy, tidy and logical answer to the question. But my reasonable take was rejected and dismissed several times. Since then, I've seen books like Bush's Cut Throat (1932) and The Case of the Missing Minutes (1936) labeled as impossible alibi/crime novels. I famously overpraised the former and think the latter is a fine, Golden Age detective novel, but both fall squarely in the first category with their (SPOILER/ROT13) znavchyngvba bs pybpxf. Brilliantly done in both cases, of course, but they're not impossible alibis/crimes.

I'm not a fan of this developing trend of lumping every alibi story, no matter how good or bad they may be, in with the impossible crime story. It simply dilutes, what's otherwise, a distinctive and somewhat unique subgenre/off-shoot by adding an untold amount of novels and short stories to the list. Every detective novel or short story that played around with simple or complicated alibi-trick suddenly becomes an impossible crime story. When nearly everything is an impossible crime, nothing really is an impossible crime. Just a whodunit with extra hurdles.

Why so many insist on counting alibis as impossible crimes without discrimination is a bit baffling to me. I suppose one of the reasons is that there aren't many actual clear cut examples of the physically impossible alibi outside of Monk. There's one rather famous and celebrated classic, but acknowleding it as an impossible alibi counts as a spoiler (ROT13: ntngun puevfgvr'f qrngu ba gur avyr unf n qbhoyr vzcbffvoyr nyvov nf bar bs gur zheqrere'f nccrnef gb or vapncnpvgngrq ol n thafubg jbhaq, juvyr gur bgure vf frqngrq naq thneqrq ol n ahefr). Another problem is that from the few genuine examples some are borderline cases (e.g. Arthur Porges' "Coffee Break," 1964) and, according my definition, the impossible alibi is inextricably-linked to the Birlstone Gambit – casting a character thought to be dead as the killer. One of the detective's story oldest tropes, but not a universally beloved one with more than it's fair share of critics.

So lacking some good, clear cut and non-spoilerish examples, the alibi-tricks from Bush's Cut Throat and The Case of the Missing Minutes might look like impossible alibis because they apply considerable ingenuity to the problem. The kind of tricks you would expect from a first-class locked room mystery, which is why I lavished so much praise on the former. But they still rely on (ROT13) znavchyngvba bs pybpxf. I simply can't call them impossible crime novels.

Japanese mystery writer Tetsuya Ayukawa described the difference between impossible crime and unbreakable alibi as the former being an alibi in space and the latter as a locked room in time. I believe the important difference between an unbreakable and impossible alibis is the difference between external and internal. The unbreakable alibi depends on outside evidence like witnesses or tempered clocks (external), while the impossible alibi solely depends on the murder's physical state or whereabout (internal). But, once again, very few agree on what, exactly constitutes an impossible alibi.

The fact that this question was raised nearly a decade ago and we're still arguing when a cast-iron alibi becomes an impossible crime is perhaps the best argument against categorizing them as impossible crime. So propose to keep treating them as two separate, distinctly different, subcategories/off-shoots of the howdunit and put this muddied discussion to bed. Well, the comments are open. So you know where to air your grievances.