By John Sweeney
BBC News, Russia
Thousands of Russians may have been poisoned by bootleg alcohol containing medical disinfectant causing drinkers' skin to turn yellow before they fall dangerously ill or die.
Pskov is the end of the line. I got off the Moscow overnight express and the earth started to buckle in front of me.
On the Pskov express I had played chess with a couple of Russians, the vodka bottles had come out, and soon every move of a pawn was celebrated with a toast.
If you're interested, I was about to win when the Russian bloke nicked my queen - anyway, I had had enough to drink to kill a small horse.
There is something about the light - or the lack of it - that eats the soul in Russia, that makes you drink. The dark days in winter, the grimness of ordinary life. They say one in six Russians is an alcoholic.
That is why President Putin, the former KGB man, is something of a puritan - at least in public.
He has brought in a series of laws, tripling the price of vodka and threatening dire penalties if people drink black market moonshine, which they call samogon.
And that is, of course, what everybody who can't afford shop-bought vodka does.
They called it the yellow death. It started in the summer when dozens of people turned up in casualty, a vile shade of yellow.
The dozens turned to hundreds, then a thousand. The better cases recovered, but will die long before their time.
The worst cases? Natasha is not yet 30, she's got a seven-year-old boy called Maxim and she has less than a year to live.
Her whole body has gone yellow - an instantly recognisable feature of toxic hepatitis.
Something has destroyed her liver and now all the natural toxins in the body are stacking up.
Her own body is poisoning her and there is nothing medicine - or at least nothing state medicine in Russia - can do about it.
Natasha and everyone else in the hospital corridors had bought samogon, moonshine, as usual - but something had been added to it.
In Pskov, the authorities have tracked more than 1,000 poisonings with 120 dead.
John Sweeney wonders what the counterfeit alcohol contains
Across Russia as a whole, officials have not counted, but some estimate 10,000 poison cases and 1,000 dead.
So who is responsible for this mass poisoning? I had gone to Pskov to try to get to the bottom of the yellow death.
We made friends with a gentlemanly Russian, Alexei, who was also an alcoholic, gave him a secret camera bag and sent him off to buy the samogon moonshine.
The plan was that we would then get it tested and analysed to see what the problem was. He bought the stuff for 20 roubles ($0.80, £0.40), a clear liquid in an old Coke bottle. I had a quick sniff.
The bouquet - rocket fuel with a touch of boot polish. And a quick gulp.
In the film Flash Gordon, the heroine is given a slug of bright green alcohol so that she can bear to sleep with Emperor Ming The Merciless. It tasted something like that.
We filmed the local cops going round busting all the little people, the street traders in samogon.
The local chief of police in Pskov, Gen Sergei Matveyev - a plump bureaucrat with a fatter gold watch - was not keen to tell me what was the most likely source of the poison.
Not many in authority give much of a damn about the nameless wretches of the earth: winos, moral degenerates.
The sense that many of the yellow people were ordinary Russians who had been poisoned through no great fault of their own seemed to be missing.
A doctor told me that the most likely cause was something which had been added to the moonshine - polyhexamethylene guanide hydrochloride.
And that stuff had got on the market as a medical disinfectant, Extrasept. It was 95% pure alcohol and tax exempt - making it cheaper than moonshine.
Dodgy traders had mixed the cheaper Extrasept with the home-made samogon - and made a killing.
It was only once I had learnt about polyhexo that I got seriously worried about the samogon I had drunk. It might have been contaminated too. Had I poisoned myself? Was I going to turn yellow, too?
We set off from Pskov to St Petersburg, to the Institute of Toxicology. They had been feeding Extrasept to rats. The results were inconclusive. I brought along a little bottle of the stuff I had drunk. They tested it and they found no polyhexo, so I was clean.
The Extrasept factory was a vast sprawling mess in Alexandrov - a town associated with Ivan the Terrible.
The technical director said there was nothing wrong with his product - and he even drank some to prove it. I asked him: "You're not afraid of turning yellow, are you?".
Later, when we got back to London, we had Extrasept tested on human liver cells - and it killed every single one.
From Our Own Correspondent was broadcast on Saturday 10 March, 2007 at 1130 GMT on BBC Radio 4. Please check the programme schedules for World Service transmission times.
John Sweeney will also be reporting on Russia's yellow death for This World on Wednesday 14 March, 2007 at 1900 GMT on BBC Two.