A two-year-old boy called Kevin ate a hamburger on holiday with his family. Ten days later he died, his organs overwhelmed by a mutant form of the E coli bacterium found mostly in feed lots or so-called concentrated animal-feeding operations - vast animal-fattening centres, without a blade of grass, where cattle stand up to their ankles in muck all day. These are where America now produces much of its beef.
Robert Kenner's film Food Inc, released in Britain tomorrow, follows Kevin's mother, Barbara Kowalcyk, though the offices of Capitol Hill as she lobbies politicians to pass Kevin's Law. This would re-empower the US regulator, the Food and Drug Administration, to close down meat processors that regularly distribute contaminated meat. It is amazing that it does not have these powers, or rather that they have been taken away by industry lobbying. It turns out that many of the people who sit, or sat, at the head of the FDA came from the industry it is supposed to be regulating.
There is no doubt that Food Inc - based on Eric Schlosser's Fast Food Nation and Michael Pollan's The Omnivore's Dilemma - is a powerful and forensic film with an unerring eye for human stories about the cruel US industrial food system, which abuses animals and workers in many ways.
British audiences, however appalled, are bound to look away and say: it can't be that bad here, can it? They will be right, up to a point. There are no British equivalents of the feed-lot operations that turn subsidised maize into meat that sells for less than vegetables. We have banned growth hormones and still rear most of our cows on grass. Our regulators are independent and have not so obviously been corrupted by political and legal appointments.
Yet feed lots have crept into Italy. American pork producers, such as Smithfield, now have vast operations in Poland and Romania.
There are signs that the downside of super-efficient, globalised agriculture is coming our way: it's already within importing range of our supermarkets. The film may just be, as Schlosser put it drily to me last week, a preview of coming attractions.
The beef, chicken and most processed food found in American supermarkets all have one thing in common: they depend on cheap subsidised maize, which Americans call corn. The United States subsidises maize in disgraceful ways, just as the European Union used to subsidise other commodity crops. Subsidies encourage the use of fertilisers, boost carbon emissions and skew the whole American agricultural system to make the unhealthiest calories the cheapest.
Yet, I hear you saying, this maize dependency is an American phenomenon. And isn't industrial agriculture the price that has to be paid for feeding the world?
Well, maybe - but I know representatives of British farming who have emerged from the film pretty shocked by what could happen to them at the hands of the monopolistic agri-industrial corporations that are the villains of Kenner's film.
We see big chicken processors enslaving smallholders by insisting on constant "improvements" that keep them in debt. We see big companies exploiting immigrant workers. We see investigators hired by Monsanto prosecuting farmers suspected of keeping patented genetically modified seed for re-use the following year. For farmers, this is scary.
And for the rest of us? We have just a slim chance in global markets to influence our future. We can vote three meal times a day by using our power as consumers to promote the kind of local, sustainable food that we want.
But those of us who call for proper food increasingly face the accusation from advocates of intensive agriculture that we are being unrealistic and elitist, because only the rich have the luxury of fussing about the provenance of their food; the poor just need to eat.
Food Inc strikes this argument a killer blow. The camera follows a Mexican-American family around southern California. The quietly articulate father has diabetes. The mother explains that she would like to cook her children healthy meals, not give them hamburgers, but she has no time because she works long hours and they cannot afford it. You can buy a double cheeseburger for 99 cents. You will pay more than that for a head of broccoli. American industrial agriculture makes the poor the most likely to become obese and get diabetes.
Kenners film argues persuasively that it is ordinary working people who are the real victims of America's super-efficient, industrial form of agriculture. The rich will always eat what they want.
It follows that we in Europe should be vigilant against Food Inc slipping in by the back door. We should try actively to prevent Food Inc becoming Food Ltd.
As Schlosser puts it: if you see someone ahead being clubbed, you don't go further down the alley. His point is well made. I recommend you see this film.