A man walks into a room. Let's say he's 50-ish, greying, slightly dishevelled. What is his story? If he's a Russian, one of his grandparents might have died in the siege of Leningrad and another in the purges. After the grind and humdrum heroisms of the Soviet Union, he might have lost his savings and home to the hyperinflation and rackets of the 90s. Maybe along the way he fell in love, had children, did the commonplace things that make up the whole drama of lives lived elsewhere.

All lives are interesting, and one of the jobs of fiction is to prove it. Still, that task is easier if they are Russian – which helps to explain why, as well as spewing out renegade oligarchs and rogue spooks, Russia has recently inspired an abundance of novels. I mean, specifically, novels set there by English-speaking authors, from thrillers such as Martin Cruz Smith's Arkady Renko mysteries, to Helen Dunmore's Leningrad books. (By contrast, surprisingly few home-grown, contemporary Russian writers have found wide foreign readerships. The Putin era has not in general been conducive to great literature.) The vogue for Russian-themed novels reflects Russia's enticing turbulence. But I think it also tells us something about our own moral anxieties.

The country's appeal to Olga Grushin, Gary Shteyngart and David Bezmozgis is easy to understand. They were all born in the Soviet Union, emigrating to North America as children. They inherited a folk memory of suffering, plus the minutely descriptive Russian language. The dying Soviet Union, in which shortages could sometimes be overcome by ruses and yarns, was a natural breeding ground for fabulists. Finally, a system that had seemed adamantine crumbled; the world broke open (Grushin's The Dream Life of Sukhanov wonderfully captures the disorientation caused by this rupture). Add the galvanising effects of immigration to that legacy and you have a propitious background for novelists.

Writers born elsewhere tend to be captivated first by the grandeur and reckless honesty of the great Russian authors; some might always view the country though the prism of Tolstoy, Dostoevsky, Chekhov and Vasily Grossman. But modern novelists are also drawn in by the same historical electricity and convulsions that fed those giants' work. Think of James Meek's magnificent civil-war saga The People's Act of Love, which features castrates, cannibalism and stranded foreign armies: all-too-real elements of the Russian 20th century, with its camps, famines and mass murder, the whole doomed, rotten Soviet experiment.

Relatively calm though the country's recent past has been, and volatile as other parts of the post-9/11 world have become, Russia's sheer eventfulness is still a pull. It is still more an empire than a state, with an empire's patchwork variety and quirks. As an old joke has it, Russia is again in a period of transition between two periods of transition. It remains a place where anything can happen, and does: shamanism in Buryatia, sectarianism in the Caucasus, and capitalism, or at least a warped Russian version of it, more or less everywhere. A great slab of unprocessed pain sits toxically at and on the country's heart.

So the satire on St Petersburg and the Caucasus in Shteyngart's Absurdistan, or the apparitions and magic realism of Gina Ochsner's under-noticed The Russian Dreambook of Colour and Flight (in which feral children discover a crack in the earth's surface), are only slight inflections of the lurid, unstable modern Russian reality – just as Bulgakov's surrealism in The Master and Margarita or The Fatal Eggs was only a mild caricature of the caprices and excesses of totalitarianism. As a visitor to such a country, you often ask: what am I doing here? As a writer you wonder: maybe I should do something with this.

There are multiple ways to think about Russia's extremes. The obvious one is physical. Much of the vast country is lethally cold for half the year or more. Virtually any outdoor activity – starting a car; walking down the obstacle-course, snowbound streets – can be its own microdrama. This harsh environment helps to explain why Dostoevsky and others always seem to be stretching up their hands to heaven. The fundamental questions – Why are we here? Is anyone in charge? – somehow seem sharper at -20C, or on a three-day train ride.

In my own novel Snowdrops, I've tried to convey the drama of the Russian seasons, from the long oblivion of the winter, through the redemption of the spring to the opportunistic explosion of the summer – and the way, along with their practical burdens, the winter and the snow shape psychology and the rhythm of Russian life. A "snowdrop" is a corpse that lies buried or hidden in the snow until the thaw; also, in my book, a metaphor for dark, close and ultimately inescapable truths that the narrator, a drifting thirtysomething English lawyer, would prefer not to think about.

Another way in which Russia is polarised is in morality: in the range of individual responses to its acute moral challenges. Good times are somehow better in Russia – something about the fact that they might abruptly end – and so are good people. The country gestates bona fide saints, whose fictional avatars crop up in 19th-century Russian literature. Modern western writers are typically more interested in characters who would like to be, but aren't quite, good; people willing to make accommodations, up to a point; keen to do no harm but also to suffer none, like the anguished Soviet detective in Tom Rob Smith's Child 44, or Grushin's Sukhanov, a sell-out art historian with a blighted conscience and a tragic past.

The saints and the compromisers face those choices because of Russia's distinction at the other end of the ethical spectrum. "The nightmare country", Martin Amis calls it in House of Meetings, his fierce tale of the gulag and its afterlife: "And always the compound nightmare. Always the most talented nightmare." The lavish cruelty of mad tsars and Stalin is past; their successors are merely brutal and dismally corrupt. Conspiracy theories thrive in Russia, and in stories set there, because, well, there are conspiracies. For Amis and others, the mystery of Russia is also, in the end, the problem of evil.

Yet just as travel writing chronicles the traveller's preconceptions as well as his journey, so for some novelists, Russia is not, or not only, a sort of moral zoo, which writer and reader can visit with a safe sense of superiority. It is also a place to test their moral pride and presumptions.

Russia has for centuries been a distorting, fairground mirror for the west. It is both like and unlike the tamer nations. Throughout the cold war, it was alien, unknowable, the other, enemy world, and an easy setting for thrillers. Something of that menace persists, partly in the guise of the Russian mob, one of the elements in John le Carré's latest book Our Kind of Traitor. At the same time Russia is European, notionally Christian and industrialised. It has a familiar high culture and recognisable architecture. Go to Moscow for a day or two, and you might consider it a normal northern European city, with extra neon and worse roads. You have to stay a little longer to uncover the wildness. As the Marquis de Custine put it after visiting in 1839, it is "only too easy to be deceived by the appearances of civilisation".

One question posed by some novels set in Russia is whether this place that sometimes looks the same actually is the same: whether everything that happens there could happen here too, could happen to us, if we shed our inhibitions and our own "appearances of civilisation". Shteyngart's hero in Absurdistan is a Russian educated in America, whose comic odyssey is in part an inquiry into how different those two parts of his identity really are. Le Carré's British establishment, meanwhile, is suavely susceptible to Russian cash.

Would we have informed in the 1930s if our lives depended on it? Would we cling to our integrity today, if almost everyone about us was selling theirs? That last is a question my own novel tries to pose. Nick, my narrator, is sucked into Moscow during its greedy, oil-fuelled boom. He only finds out what sort of man he can be, perhaps has always been, when he lives in Russia.