One could call Robert Kenner's brave documentary Food, Inc. "An Inedible Truth." Graphics turn the film's titles into labels at a supermarket, which is the perfect place to start; at the market, we're lulled by images of red barns and green fields. "The veil is drawn," announces Fast Food Nation's author Eric Schlosser, who charges that our food has changed more in the past 50 years than it has in human history.

We can see that change vividly in Food, Inc., as when we drive past the Concentrated Animal Feeding Operation on Interstate 5, its odor present for nine miles. Defying the lawyers, one corporate chicken farmer shows us her wretched, antibiotic-packed birds in a pile, so genetically breast-plumped that they're unable to walk more than a few steps. Lobbyist foxes patrol these mega-henhouses. Today's industry lobbyist is tomorrow's regulator, as sure as today's pig is tomorrow's bacon, and the sharecropper-waged farmers aren't in any position to complain.

From the air, we visit Tar Heel, N.C., site of the world's largest slaughterhouse. Hidden cameras show us the inside. Kenner tells of how Big Ag recruits bankrupt Mexican corn farmers—driven out of business by cheap American corn, thanks to NAFTA—who were solicited in their own country to do this dangerous and poorly paid pig butchering.

Drooling, packed-in steers—actually seen herringboned into a freight car in one overhead shot—are fattened with cheap Iowa corn. It breeds E. coli in their guts. The nearly annual outbreaks of E. coli are seemingly the cost of business, a price paid even by spinach-eating vegetarians.

Meanwhile, interviewee Barbara Kowalcyk tries year after year to get a law passed to allow the USDA to close down toxic slaughterhouses. The law is to be called Kevin's Law, after her two-and-a-half-year old son who he was killed by a bad hamburger from a plant that dawdled for weeks over whether to recall its tainted meat. She describes what it was like to watch her child die, but she has to watch what she says; it's a felony to libel hamburger in Colorado. No, that's not a joke.

Prefer tofu? Monsanto hires frightening investigators to make sure that no farmers save the seeds from the company's patented soybeans, now grown in a 90 percent market share in the United States. Too bad genetically engineered pollen doesn't recognize a fence, as many farmers have discovered in court.

Food, Inc. tries to end upbeat by counseling fine-print reading, farmers market attendance and gardening. It's suggested that we pressure the FDA to monitor mega-slaughterhouses instead of harassing smaller agriculturalists; one such is the slightly messianic Joel Salatin of Polyface Farms in Virginia, who gladly allows us to watch how the chickens get it in the neck on his spread.

As director, Kenner can't be accused of starry-eyed idealism. These days, even Wal-Mart gets into bed with organic growers. We see two of their reps paying a visit to as perfect-looking a Vermont dairy farm as you ever saw on the side of a lunch box. The film ends with a Woody Guthrie anthem and the reminder that if the United States could make Big Tobacco heel, that agribusinesses' wasteful and deadly practices can be stopped.

You need to see this film. In one and a half enlightening and enraging hours, it's a tutorial on what's on the other end of your fork.

'Food, Inc.' opens on Friday, June 19, at the Rialto Lakeside Cinema, 551 Summerfield Road, Santa Rosa. 707.525.4840.

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