MOST PEOPLE don't behave all that well in a crisis, according to Fernando Meirelles in his new film, Blindness. Jam them together in a small space under extreme duress, and they will revert to their most primitive instincts, turning on each other in animalistic fury. Sorta like the financial-bailout meetings in Washington last week.

The film, based on a 1995 novel by Portuguese Nobel Prize winner José Saramago, sets up an extreme test condition and then runs its nameless—hence universal—characters through their paces to see who degenerates and who clings to a shred of decency. The premise resembles a traditional horror or sci-fi movie—an unexplained plague scythes through modern civilization—but the intent is more psychological than apocalyptic. The plague happens to be a peculiar form of blindness, one that leaves people lost in a sea of milky whiteness instead of pitch blackness. It could have easily been zombie-ism (the 28 Days franchise), a natural toxin (a la The Happening) or drifting radiation from a nuclear explosion (take your pick of 1950s sci-fi cautionary tales).

In an unidentified metropolis, people start losing their sight. The initial concern that the blindness is contagious seems like an excess of paranoia. In the first of many metaphors that Meirelles throws against the screen hoping that one will stick, he echoes the irrational fear of people with AIDS.

As we gather up a band of the afflicted, however, it appears that they have indeed been rendered sightless by serial contact. The first victim (Yusuke Iseya) has his car robbed by a faux Good Samaritan (Don McKellar, who also wrote the script), who then whites out. After seeing the initial victim, an ophthalmologist (Mark Ruffalo) succumbs, which is a nice touch of irony that makes him the eye doctor who can't heal himself. His receptionist and two patients (one of them being Alice Braga) follow. Only the doctor's wife (Julianne Moore) keeps her vision, for reasons unknown. (In a more familiar scenario, the wife, being immune, would carry the hope for a cure in her genetic makeup, but Meirelles has an even nobler role in mind for her.)

When the government starts trucking the blind to quarantine camps, Moore's character feigns blindness in order to stay with her husband. The camp is really a prison where even the guards won't patrol—they stay outside the walls at a safe distance. The occupants are fed, and that's it. A droning voice on a TV monitor assures them that all steps for their welfare are being taken.

In a parody of society's bureaucratic urge, the various wards elect representatives and attempt to govern humanely. Ruffalo's doctor plays the well-meaning liberal in this metaphor. Unfortunately, baser patterns quickly surface.

The thief starts sowing discord (McKellar, who was very funny as an egotistical director on the Canadian series Slings & Arrows, pushes his semilovable creep too far into Kevin Pollak territory).

He's just a taste of what's to come when a genuine bad guy (Gael García Bernal having a high old time) and his criminal cronies hoard the dwindling food supplies. Somehow commandeering a gun (where did that come from? the film falters on details like this), García Bernal's character starts demanding tribute from the other prisoners, even ordering them to send in the women to be raped.

The horrors that attend the breakdown of civilization in the quarantine zone are genuinely harrowing—at times the trash-strewn hallways filled with jibbering, naked inmates make The Snake Pit look like the Betty Ford Clinic. Meirelles and cinematographer César Charlone experiment with a variety of techniques—fuzz focus, an all-white screen, brutal grainy close-ups—to immerse us in this disorienting world.

After so much despair, Meirelles then releases his core characters, allowing them to search for redemption outside the prison. At this point the film loses momentum and begins to feel like a long march to a fuzzy finish line.

Moore gives a solid performance, evincing terrific sinew as she slowly becomes the de facto leader of her dependent charges—a seeing-eyes matriach. An early scene, pre-plaque, in which she drinks a too much to compensate for her husband's emotional testiness, is nicely balanced later by her steely response to his moment of weakness with another inmate. Too bad then that Danny Glover has to play that all-too-familiar character the beneficent old black man; even worse, in one very miscalculated scene, Glover's character recites, as if reading a satirical fairy tale, the government's doomed-to-fail efforts to cope with the epidemic. He then holds up a transistor radio that plays a sappy ditty that sets the poor wretches' toes to tapping.

Ultimately, Meirelles wants us to believe that our individual natures can be bent but not broken. The good sink low but come to rest on a solid moral strata, while the bad have no internal barriers to stop them from plunging all the way to the bottom. The point is reinforced by one of the rapacious characters, who was blind from birth and uses his heightened sensory skills in all the wrong ways. "How could you? You're supposed to have empathy and human decency," Ruffalo shouts at him in high dudgeon.

Everything Meirelles and McKellar want us to take away from Blindness can be found in more modest, less visually adept genre movies. Twenty-five years ago, this could have been a great John Carpenter vehicle.

BLINDNESS (R; 120 min.), directed by Fernando Meirelles, written by Don McKellar, based on the novel by José Saramago, photographed by César Charlone and starring Julianne Moore, opens Oct. 3 at selected theaters.

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