Twenty months ago I set out to examine each of the ten rules in Ronald Knox’s detective fiction decalogue in laborious detail; this month, that project will finally be completed. Then I can finally return to The Criminous Alphabet, eh?

Here are the links to everything:

Concerning the declaration of clues, arguably the defining precept of the Golden Age, Knox says:

The detective must not light on any clues are not instantly produced for the inspection of the reader. Any writer can make a mystery by telling us that at this point the great Picklock Holes suddenly bent down and picked up from the ground an object which he refused to let his friend see. He whispers ‘Ha!’ and his face grows grave — all that is illegitimate mystery-making. The skill of the detective author consists in being able to produce his clues and flourish them defiantly in our faces: ‘There!’ he says, ‘what do you make of that?’ and we make nothing.

If I had to pick a single aspect of detective fiction to explain what makes it so appealing to me — and you’ll be surprised to learn that I almost never do, as if the people I meet day-to-day aren’t interested or something — it would be that sudden reversal of realisation that comes from having been completely wrong in your interpretation of a clue. I have spoken before about what I consider to be perhaps the finest example of this that the Golden Age ever produced (no, I’ll not name the book again, since it runs the risk of spoiling it for the exceptionally watchful reader), but what’s so wonderful is that the era is littered with examples…indeed, so jam-packed that single books contain multiple examples. The holy grail of this is arguably the situation in which the misinterpretation of one clue results in the misinterpretation of another and so on and so forth until you find yourself miles away from the correct answer simply by an unassailable chain of logic built on one faulty piece of reasoning. Aaah, good times.

Perhaps the closest we came to that in the Golden Age was The Poisoned Chocolates Case (1929) by Anthony Berkeley, in which an apparently simple poisoning is provided with no fewer than six distinct solutions (and Martin Edwards even found space for a seventh — and I think there’s ground for an eighth) based on subtle interpretations of various points. It’s interesting to note, then, that Berkeley, who is often seen as one of the most important figures in the development of Golden Age detective fiction — and I’m not going to disagree with that — wasn’t really all that bothered about this open declaration of clues that we’ve come to call ‘fair play’. Right from his debut The Layton Court Mystery (1925) it was clear that Berkeley was more interested in form ahead of function, preferring to play around with solutions and structure than worrying his head over precisely how such conclusions could be reached while also declared to the reader:

“Not much so far as actual hard-and-fast-evidence goes, I’m afraid,” [Roger Sheringham] concluded, “but we greater detectives are above evidence.”

I would suggest that the fair declaration of clues is the underpinning precept of the Golden Age, its inclusion as a matter of course being the point at which detective fiction stopped being the easy provision of answers that you had no investment in and instead became a game where you were genuinely given the opportunity to get to the answer ahead of the characters. The lunatic fringe that insists on Trent’s Last Case (1913) by E.C. Bentley aside, there’s a reason we talk about 1920 as the beginning of the Golden Age: because it saw the publication of The Cask (1920) by Freeman Wills Crofts and The Mysterious Affair at Styles (1920) by Agatha Christie, two novels whose authors went to great lengths to provide verbatim evidence for the reader to actually examine. The idea was hardly original, given that floorplans and specific dimensions of rooms had been a feature of stories long before this, as had evidence of interpretation that required no reproduction of footprints or handwritten letters, but when you compare the footprint diagram in Crofts’ debut with the sudden changing description of footprints in The Mystery of the Yellow Room (1907) by Gaston Leroux there’s a distinct change in intent. Leroux wants you to be amazed by the brilliance of his sleuth, Crofts wants you to be amazed at your own inability to see that which was right in front of you…and impressed by the perspicacity of the sleuth who did see it.

Were this concept not an exciting one, it’s fair to say that these two books, which brought not a huge amount else that was genuinely new to the crime story — please note, I’m not saying they’re not good books — would doubtless have been lost amidst the many others published that year and the school of crime fiction that resulted would have doubtless looked very different. Inspectors Burnley and Lafarge aren’t so very different from Dicken’s Mr. Bucket in Bleak House (1852) — they have the same tenacity, the same subtle way of making their will felt and ensuring they get the co-operation they need — and Hercule Poirot is an slightly humanised unknowable genius in the style of the various pretenders who sprung up in the wake of Sherlock Holmes, feeling to me somewhat closer to Dr. John Evelyn Thorndyke than Doyle’s creation (that’ll upset someone, I’m sure) if due to nothing more than his willingness to lean heavily into practical science and psychology. These were very much the same broad types we’d seen before, mutatis mutandis, and more of the same was not going to elicit the excitement that saw Crofts and Christie both open their accounts with such great sales.

A piece of Golden Age detective fiction is obviously defined by more than just its ability to declare its clues, as demonstrated by the sheer volume of stories produced under that banner which did no such thing, but this declaration when we see it — and, be honest, you’ve sort of come to expect it in books from this era, right? — became a feature enough of the time that it signified something meaningful as a development of how crime stories were being written and what they were setting out to achieve. When Anthony Horowitz drops a frankly brilliant piece of in-yer-face clewing in Magpie Murders (2016) or offers up a subtle variation on an oft-cited example from Hercule Poirot’s Christmas (1938) in The Sentence is Death (2018), those of us who enjoy our classic-era fiction get excited because we’re being invited into the game in a way that recalls Crofts’ reproduction of that footprint. It’s easy enough utilise the principle of the solution in, oh, say The Man in the Queue (1929) by Josephine Tey because…well, there’s not really much in the way of clued build-up to that. Doyle did this, G.K. Chesterton did it, Gerald Verner did it, Edgar Allan Poe’s Auguste Dupin flourished before us a sailor’s knot and a newspaper clipping mere moments before ushering in the solution to The Murders in the Rue Morgue (1841) — dammit, anyone can do that. The challenge is showing me what you’ve had all along — “defiantly in our faces”– which is more than sufficient to solve the crime, “and we make nothing”.

There’s an additional element to this, too, that I’d love to talk about in greater depth at some point: the Challenge to the Reader.

The modern, more realistic bent of a lot of crime fiction is somewhat inimical to the Challenge to the Reader, which introduces an element of artificiality by reminding the reader that they are, in fact, reading a piece of fiction, but I think it’s one of the most brilliant innovations the genre ever devised. In essence, the CttR is placed in a book at the point in the story by which all the information has been provided to the reader, and informs the reader of this and invites them to put the preceding information into a pattern that explains the mysteries in the text. As Rupert Penny said in the Challenge in his debut The Talkative Policeman (1936):

At this point the intelligent reader, if he has not already done so, should be able to attempt the solution of the problem with every prospect of success by taking thought, eked out where necessary with a guess or two. … Since nothing can too strongly express condemnation of those who use guesswork alone, making no attempt to exercise their reason upon the product of their imagination, nothing will here be said. The book was not written for them.

Such a Challenge is simply the game-playing of GAD raised to another tier — reminding you that the answer is within your grasp, and encouraging you to engage in what is, after all, the raison d’etre of this type of book; whay read something that’s going to give you the clues if you’re not then going to use them? I’ll be honest, I wish every detective novel contained a Challenge to the Reader, and I legitimately think it’s a shame that the conceit has dropped out of use. Not only does it reassure you that you’re now able to answer everything — no sudden newspaper articles or squinting butlers will drop in at the last moment to clarify things, you you can take time to think in the knowledge of being fully informed — but it’s also good for the author to ascertain that they’ve included the information the reader needs. Yes, much as not every GAD novel plays fair, not every Challenge to the Reader guarantees you’ve been given all the information you need (grrrr…) — and, in both cases, those that don’t form an unfortunate subset of the genre overall — but when they have and you can…man, that is pure reading nirvana.

Well, okay, not quite. There is a better possibility.

The very best, most purely enjoyable Challenges to the Reader don’t simply reassure you that you’ve been told everything, they also — as did Penny in Sealed Room Murder (1941), as did James Scott Byrnside in The Strange Case of the Barrington Hills Vampire (2020) — provide you with a list of specific questions for you to answer. This is delightful for two reasons: first, you can be fairly reassured that the author will have taken the effort to ensure than you can actually answer questions they are drawing your attention to, and second, the questions drawn to your attention are undoubtedly key to the core of the mystery and you often have no damn clue what the answers are. That Rumsfeld-esque sensation of knowing that you know what you need to know and yet feeling completely foxed by the very pointers being dangled tantalisingly in front of you is, for me, the exact sensation I hope my detective fiction elicits. If more authors in the Golden Age had been pushed to include specific questions to ensure the reader was well and truly tied up in sheer perplexity, requiring them to have hidden the clues cleverly enough for the attentive genre nerd to have overlooked even one of those answers…man, just imagine that book after book after book. I mean, sure there would be about half as much published in the genre, but given how much of it is forgotten, mediocre, or both, I don’t reckon we’d feel that GAD was any less hale and hearty as a result.