There is a marvellous image at the beginning of White Fever, an account by Polish journalist Jacek Hugo-Bader of his demoralising road trip across Siberia. He is driving his Russian jeep along the great flat steppes between Ufa and Kazan. The traffic is hardly moving: in front of him are two lorries, one pulling the other on a tow-rope. He overtakes. At the top of the hill a traffic cop pulls him over. Reluctantly, the journalist hands over a 1,000-rouble bribe. (Overtaking on a solid line in Russia is a serious offence.) When he drives off and looks back he sees the lorries turning round and going back down the hill to begin their laborious climb once more  the scam is another ingenious example of how the Russian state fleeces its citizens.

Two decades after the collapse of the Soviet Union, Russia has failed to come up with a new national idea. Instead, the US's erstwhile superpower rival has metastasised into a brutal kleptocracy. (This, at least, is the damning verdict of US diplomats, revealed late last year by WikiLeaks.) In a four-month drive from Moscow to Vladivostok, punctuated by frequent breakdowns and one nasty incident in which he slithers off the road into the snow, Hugo-Bader explores this despairing post-communist landscape.

Ideology has disappeared. Instead, other beliefs have filled the vacuum. He finds shamans and former hippies. He travels to a remote community in the Siberian taiga where several thousand people live and worship a Russian Christ. (The Christ's real name is Sergei Torop. A former militiaman, he styles himself Vissarion, claims to have 100,000 global followers, and is fond of issuing commandments on sex, children and how to boil water to make tea.) This is the only place in Russia, Hugo-Bader writes, where he comes across happy people  "cheerful, jolly, calm people who actually greet a stranger in the street".

While some Siberians have turned to mysticism in search of meaning, others cling to the old Soviet faith. The author drops in on Mikhail Kalashnikov, the 88-year-old inventor of the famous rifle. Kalashnikov is unrepentant about his deadly creation. He is also selectively deaf when the journalist grills him about the Soviet invasion of Poland, in which he participated as a young solider. He describes himself as a patriot of the fatherland  by which he means the now-disappeared USSR.

The title White Fever is a reference to vodka. Or, more accurately, to the weird hallucinogenic state that Siberia's indigenous tribes fall into when they drink too much of it. Alcoholism is wiping out entire peoples. To the Evenk tribe it is, Hugo-Bader suggests, "the equivalent of Zyklon B". After vodka, the Evenks get undressed in the freezing cold, lie on railway lines, or shoot themselves in the chest with hunting rifles. In 1985, when Mikhail Gorbachev came to power, the Evenk village of Bamnak had 17 reindeer herders. By 2007 none were left. They had drunk themselves to death, committed suicide, or disappeared under the ice.

Hugo-Bader sees further depressing evidence that Russia is slowly killing itself. As well as alcoholism there are the traffic accidents (32,000 dead in 2007, as many as in the whole European Union). And there is rampant drug abuse and HIV. Three million Russians are believed to be carrying the virus, with almost a third of them in prison. One of the first things that struck me as a correspondent in Moscow, overlapping with Hugo-Bader, was the absence of old men. There weren't very many of them. Russian male life expectancy hovers under 60.

And yet White Fever includes plenty of unexpectedly joyous moments. During his epic car journey, Hugo-Bader encounters other travellers  a 22-year-old Vladivostok prostitute content with her lot, and a wandering Chinese man, riding on a horse from Moscow back to Beijing in time for the Olympics. Amid the devastating Aids epidemic, he meets Svetlana Izambayeva  Russia's Miss HIV positive. Svetlana gives haircuts to other carriers. She runs a support group and has a TV programme. She has fallen in love, and given birth to a healthy daughter.

The strength of this book is that it dwells on human stories that lie outside the parameters of conventional newspaper reporting, and the translation from the Polish by Antonia Lloyd-Jones is pitch perfect. White Fever has little to say about the current clique in the Kremlin  though Vladimir Putin appears briefly as a young lieutenant in the Leningrad KGB, when he breaks up a hippy commune. But Hugo-Bader is a sympathetic companion, and he offers a compelling portrait of a society in moral and social breakdown.

Luke Harding's Mafia State: Spies, Surveillance and Russia's Secret War will be published by Guardian Books in September.