The year 1929 was unusually grisly. At a gloomy country pile an old man was stabbed to death with a slender, jewel-encrusted Italian dagger during a game of murder in the dark. In London, a box of maraschino chocolates laced with nitrobenzene mailed to a playboy baronet was mistakenly snarfed by a housewife who died in agony a few hours later. Then a famous explorer was discovered in the bath — dead and, doubly mysteriously, transformed into a woman. In the West End, while queuing for a ticket to a hit musical, a young man collapsed to the pavement, a stiletto dagger protruding from his grey tweed coat. And pottering about her garden in St Mary Mead, a fluffy-haired, deceptively scatty old spinster was about to poke her nose into a mysterious death at the vicarage.

This virtuosic (fictional) crime spree was not the work of a single madcap genius, but a whole gang of twisted minds whose work is collectively immortalized as the golden age of detective fiction. A striking number of them were women. The Scottish playwright Josephine Tey and 25-year-old Margery Allingham both debuted their detectives (Alan Grant in The Man in the Queue and Albert Campion in The Crime at Black Dudley). Meanwhile, Dorothy L Sayers and Agatha Christie were knuckling down to the first full-length adventures for Harriet Vane and Miss Marple, two lady sleuths who would change crime fiction.

Anthony Berkeley, who would a year later set up the Detection Club (founding members included Christie, Sayers and GK Chesterton), published The Poisoned Chocolates Case, “one of the most stunning trick stories in the history of detective fiction”, according to Julian Symons’s seminal history of the genre. Beyond Britain, Georges Simenon was taking a brief hiatus from sleeping with 10,000 women to dash off Maigret’s first outing, while in America, the art critic Willard Huntington Wright was working, under the pen name SS Van Dine, on The Bishop Murder Case, a book that would make him a national sensation and (by his own description) the favorite crime writer of two presidents. In short, 1929 was one of those inexplicably dazzling years when the talent, energy and audacity of a handful of individuals collided, then fermented into something greater. It might be the most important year in the history of the crime novel.

Why was the interwar period so booming for sleuths? It’s a genre people always turn to “at times of national disaster or loss”, says Nicola Upson, who writes detective novels starring a fictionalized Josephine Tey and is the curator of Murder by the Book, an exhibition of 20th-century crime fiction at Cambridge University Library featuring original editions of The Crime at Black Dudley, The Man in the Queue and more of 1929’s finest fruits. “There’s something very reassuring about the central premise of a crime novel, that each life matters and people should be allowed to live it to their last natural moment,” she says. Ten years after the end of the war, the gaps left in the fighting generation were still stark. “We shouldn’t forget that loss and grief are at the heart of crime fiction,” Upson says.

The world changed rapidly in the Twenties — just consider how women suddenly discarded waistlines and chopped off their hair — and in many ways the detective novel was a fictional buttress against all the progress and upheaval. This is the genre that challenges, then restores, the status quo, controlling an explosion. It often leaves a strong conservative aftertaste. The fictional worlds of these writers were untouched by the postwar slump, mass unemployment and the long anticipated approach of another war. “The fairytale land of the golden age,” Symons writes, “was one in which murder was committed over and over again without anybody getting hurt.”

It’s a genre people always turn to “at times of national disaster or loss.”

By 1929 the popularity of crime had finally won it a grudging measure of critical recognition (although it continued to be condescended to — the reason Cambridge has such a well-preserved crime collection, Upson points out, is that the library never bothered to throw away the dust jackets, assuming no one would read them). It was the year that Ronald Knox unveiled his winking Decalogue, or Ten Commandments of crime writing, which instructed writers to introduce the murderer early, declare any clues the detective discovers to the reader, and make use of no “more than one secret room or passage”.

Such an approach is evidence of a belief that still persists around crime fiction: that it’s more of a puzzle than a literary enterprise. According to Knox, crime has rules not “in the sense in which poetry has rules … but in the sense in which cricket has rules — a far more impressive consideration to the ordinary Englishman.” Of course, all the best golden age crime writers broke them, repeatedly.

The confidence that took — to appear to be following a set of fixed steps, then, very deliberately, flout them — is one indication of the sheer ingenuity displayed by crime writers in 1929. The Poisoned Chocolates Case is an obvious example — a totally show-off story in which the reader is presented with six solutions to a single crime, each devised by a member of the fictional Crime Circle (an idea that Richard Osman would tweak, with some success, in The Thursday Murder Club). This sense of intellectual springiness, of improvisation, was partly the result of no one taking what they did too seriously. New initiates to the Detection Club had to swear a sombre oath eschewing the use in their stories of “Divine Revelation, Feminine Intuition, Mumbo Jumbo, Jiggery-Pokery, Coincidence or Act of God”.

Few were under the illusion, so distressingly common with novelists today, that what they were doing was particularly important. Tey, who was an enormously successful playwright, referred to crime novels as “my knitting” while Allingham called her plotting the “plum pudding method”. Beneath the jocularity lay a kind of gentle disappointment: many of these writers were intellectuals who really would have liked to have been doing something else if only the bleedin’ murder books didn’t sell so well.

SS Van Dine took up crime writing during a long bout of illness and planned to give up after six books and return to academic life. But they proved so overwhelmingly popular that he never went back to the library. His feelings about this are best expressed in the title of his 1928 article: “I used to be a Highbrow and Look at Me Now.”

Sayers, too, was a frustrated bluestocking. In 1929 she quietly published Tristan in Brittany, the first modern English translation of some dusty fragments of a 12th-century verse. Today, the poem is considered by scholars one of the most innovative and influential works of medieval literature. Honestly, Sayers was wasted on crime.

Few were under the illusion, so distressingly common with novelists today, that what they were doing was particularly important.

The other great animating force behind the whodunnits of 1929 was, of course, the detectives. There were two principal flavors: stolid, dutiful coppers like Tey’s Alan Grant (“He was a plodder. But that was the worst that could be said about him”) and the eccentric outsider, usually a spinster or a dandy. Of the latter, Sayers’s Peter Wimsey and Van Dine’s Philo Vance represent mirror images from either side of the Atlantic: spiffin’, jiffin’ poshos whose sherry-light manners conceal deeper, darker intellects. A typical Vance pronouncement to his valet might run: “Oh I say, Currie, an eminent gentleman has just been murdered in the neighborhood and I am going to view the body. Lay out a dark grey suit and my Bangkok. A sombre tie, of course.” Some people find all the affect unbearable (“Philo Vance / Needs a kick in the pance,” quipped Ogden Nash), but it has its charms too.

And what about those spinsters? In different ways, mild Miss Marple and tough Harriet Vane were products of the same postwar order. Marple was a kind of forerunner to the “surplus woman” toddling between the houses of more fortunate relatives and friends (nomads are useful for detective series). Whereas Vane was a new kind of woman, one who celebrated her overdue spate of postwar freedoms by drinking cocktails, writing books and tossing aside lovers, but still found herself battering against the same old prejudices.

In Strong Poison, the novel Sayers was writing in 1929, Vane is put on trial for murdering her lover — but really, in a world still corseted by Victorian mores, she’s on trial for her existence. Gladys Mitchell’s brilliantly weird sleuth Adela Bradley (who looked like a “reconstruction of a pterodactyl … in a German museum”), another 1929 debutante who went on to appear in 66 novels, had the audacity to be a practicing doctor.

These fictional lady sleuths provide the solution to a real question: in a year when the big literary prizes went to JB Priestley and Thomas Mann, why were so many whodunnits by people called Margery and Gladys? Why was the golden age most famous not for its crime kings — but queens? Some, like Tey, who moved back home to Inverness to care for her ageing parents after her boyfriend was killed at the Somme, were Miss Marples, women whom society could find no use for and so had time to pick up a pen. Some, like Sayers and her avatar Vane, were fed up with being overeducated but underestimated. The year 1929 was remarkable for the number of women wandering around with brains and brilliance and nowhere to put them. So what did they turn to? Murder, of course.

Susie Goldsbrough is the assistant literary editor at The Times of London