You’re a school nurse who sends home a little boy flushed with fever; you reach into a bowl of peanuts at a bar; you pick up a cell phone left on a counter. It doesn’t take much contact to become infected in “Contagion,” Steven Soderbergh’s brilliant movie about the grimmest subject imaginable: a pandemic that kills millions of people in a few months. “Contagion” is serious, precise, frightening, emotionally enveloping. It’s a highly controlled film about an out-of-control event, a film so sure-handed and intelligent that it has an invigorating, even an enlightening, quality, as if a blurred picture had suddenly come into focus. You leave the movie shaken, but also, at another level, relieved, since there isn’t a grandstanding speech (except for one by a demagogue) or an instant of melodrama. “Contagion” confronts reality head on; it’s a brief against magical thinking. Soderbergh and his screenwriter, Scott Z. Burns, may not have intended it, but their movie could become an event in an ongoing political debate over the nature of American life.

Kate Winslet, Matt Damon, and Laurence Fishburne in Steven Soderbergh’s movie. Illustration by JORGE ARÉVALO

“Contagion” moves with harrowing concentration and speed: Beth Emhoff (Gwyneth Paltrow), who is in Hong Kong on a business trip, has a night out in Kowloon, where she eats a delicious-looking pork dish at a restaurant. On the way back home, during a layover in Chicago, she sleeps with an old boyfriend, and then returns to her husband, Mitch (Matt Damon), in Minneapolis, where she suddenly becomes sick and dies. Was it encephalitis? Meningitis? At first, no one realizes that a new, flulike virus has killed her. From Hong Kong, Chicago, and Minneapolis, the virus soon spreads everywhere. Only at the end of the movie do we find out how Beth got infected. (Earlier, a researcher analyzing the virus’s cell structure says, “The wrong pig met up with the wrong bat.”) The scariest aspect of the story is that Beth wasn’t traipsing around in the jungle; she was visiting one of the most cosmopolitan places in the world. In flashbacks to Hong Kong, cued by security-camera footage, we can see her smiling happily as, after the restaurant dinner, she spends a pleasant, slightly drunken evening in a glittering casino, during which this ordinary, messing-around woman infects virtually everyone she comes into contact with. In “Contagion,” paranoia reaches its logical end point: the everyday streams of connection—the personal and professional meetings that make economic and social life and pleasure possible—become the vehicle of our destruction. In the movie’s one funny moment, a teen-age boy and girl, trying to spend some intimate time together, are reduced to wriggling side by side in the snow; the boy finally rolls onto the girl for a kiss, only to get roughly pulled off by her father. When kids can’t even make out, the world may truly be coming to an end.

Formally, and despite what Soderbergh has told interviewers, the picture looks less like a disaster movie than like an international thriller. He and Burns jump all over the world in the fast-moving, everything-happening-at-once style of the director’s earlier triumph “Traffic” (though without the dirty excitement of that drug-trade movie). As in so many international thrillers, dates and place-names are announced on the screen: “Day 5”; “LONDON ENGLAND population 8.6 million.” For once, this portentous device makes sense, since the plague spreads geometrically and inexorably in time and space, and we need to know the progress of the disease at any given moment. The movie’s tension-inducing techniques may be conventional, but Soderbergh uses them better than anyone has in the recent past. The presence of movie stars helps: their authority is part of what keeps us fascinated by the gruesome fable, juicing it a bit, so that we can actually enjoy it.

At the Centers for Disease Control and Prevention, in Atlanta, Dr. Ellis Cheever (Laurence Fishburne), the deputy director, takes charge of tracking and fighting the disaster. Fishburne plays Cheever as an imposing (though fallible) man determined to remain calm, no matter how awful the news; he’s restrained and purposeful, and the performance is effective but a little stolid. Cheever sends a medical-intelligence specialist, Erin Mears (Kate Winslet), to the Minneapolis hot zone, and Winslet, working with more edge than Fishburne, hardens her voice, sets her face in a determined mask, and captures the tone and the style of a professional woman exasperated by slowness and ignorance, a woman almost masochistic in her scrupulous sense of duty. Meanwhile, in a C.D.C. lab, Dr. Ally Hextall (Jennifer Ehle) tries to isolate the virus and develop enough of it to create a serum. She wears a bulbous orange nylon protective garment and a clear plastic helmet. Despite this outlandish getup—she looks as if she were ready for a space walk on a planet made of candy—Ehle is perhaps the most appealing scientist in the history of the movies. She plays Hextall quietly and selflessly, and her skill seems a function of her sensitivity. If this is a myth of science humanized by a female sensibility, it’s a pleasing one.

Without leaning too heavily on the obvious, “Contagion” evokes memories of the bafflement and the sense of outrage and helplessness that greeted the H.I.V. and Ebola viruses, in the nineteen-eighties, and the swine-flu scare a few years back. Soderbergh could have pumped up the horror, turning the material into a “World of the Living Dead,” with disintegrating near-zombies lurching everywhere, but doing the story straight makes it scarier than any amount of trashily morbid movie spectacle. What he gives us is terrifying enough: people get sweaty and swell up and go into convulsions. Soderbergh shows us death a few times, and then he and Burns move away from individual stories and broaden the picture. Again and again, they drive in the nail with a single blow—a sardonic turn of phrase, a pause, a silence that allows us to draw our own conclusions. As panic engulfs the country, civil society dissolves. Crowds assault banks and stores; people desperate for a cure attack pharmacies. The episodes are violent and appalling but mercifully brief.

Soderbergh, after fumbling through experiments like “Full Frontal” and “The Girlfriend Experience,” and playing at satire in “The Informant!,” has recovered the mastery that he displayed in “Traffic.” Everything in “Contagion” is staged with great physical conviction but without exaggeration—the tumult is neither overdone nor underdone. Shooting the movie himself (under the nom de caméra Peter Andrews), Soderbergh keeps the palette generally dry. And the slyly malevolent editing, by Stephen Mirrione, is superb. Shots of seemingly innocent objects—a bus pole, an empty glass, both recently touched by an infected person—are held for just an instant longer than usual. “Contagion” mostly rushes ahead, so when it slows a bit the effect is devastating, as in a heartbreaking scene in which Damon’s character can’t take in the fact that his wife is gone. The camera just stares, and Damon has a great moment.

The speed and the range of the movie are analogous to the way the disease spreads. The Internet, another system of universal connection, becomes a kind of plague, too. “Contagion” has a wild card: a soreheaded San Francisco blogger, Alan Krumwiede, played by Jude Law, with a raspy voice and bad teeth. At first, we don’t know how to take Krumwiede. He complains online that the C.D.C. is ignoring an effective homeopathic cure and colluding with big pharma on a pseudo drug cure. He has ambiguous meetings with a hedge-fund guy. He could be a heroic truthteller—a populist champion—but he could be a rancorous loser, too, cloaking his personal chagrin in left-wing tirades. Krumwiede’s aggressions echo those of 9/11 conspiracy theorists and, perhaps, of Julian Assange at his most self-righteous. As the filmmakers tell it, Krumwiede, spreading distrust, is part of the disease. Until the end, his motives remain a mystery.

“Contagion” is, of course, a 9/11-anniversary movie, though probably not one that the public was expecting. Soderbergh appears to be saying, “I’ll show you something far worse than a terrorist attack, and no fundamentalist fanatic planned it.” The film suggests that, at any moment, our advanced civilization could be close to a breakdown exacerbated by precisely what is most advanced in it. And the movie shows us something else: heroic work by scientists and Homeland Security officials. We can’t help noticing that with two exceptions—a French doctor who works for the World Health Organization (Marion Cotillard) and a renegade epidemiologist in San Francisco (Elliott Gould)—the heroes are all employees of the federal government, and instinctively factual people. No one prays, no one calls on God. “Contagion” lacks any spiritual dimension—except for its passionate belief in science and rational administration. The movie says: When there’s real trouble, we’re in the hands of the reality-based community. No one else matters. ♦