Blindness, the new film from Brazilian director Fernando Meirelles (The Constant Gardener, City of Men), is a beautifully made film about a terrible - yet all too plausible - turn of events.

It's about what happens when the protections and mechanisms of modern society break down and supply lines are cut. It dares to show us how quickly and painlessly ethics and morality fly out the door when survival is at stake. This is a hard film to watch, but I recommend you make the effort: you will leave the theater speculating about things you've been taking for granted, and find yourself returning repeatedly to the ideas introduced by the movie.

Things start to go south in the nameless urban metropolis depicted in the film when a driver (Yusuke Iseya), in the midst of big city traffic, suddenly loses his sight: his field of vision goes featureless white, and he can no longer discern the traffic signal in front of him - or anything else.

After the requisite honking of horns, cursing and fist-shaking, several commuters are canny enough to realize something beyond inattention or cell phone texting is behind the lane blockage event, and go over to investigate. One of them (Don McKellar) - upon learning of the poor fellow's debility - offers to help out by driving him home. Somewhat reluctantly (but having no other choice), the stricken man agrees.

But is this a Good Samaritan coming to his aid, or an opportunist sensing an easy mark? The nice young man even offers to help the fellow up to his apartment, and gets him settled in prior to taking his leave.

Immediately the film establishes a theme that calls into question the unequivocal quality of a "good" person vs. a "bad" one. It's a theme the narrative returns to time and again as seemingly "good" people make all sorts of ethical compromises in order to survive, while seemingly "bad" ones behave in quite similar - though certainly less self-reflective - ways. By the time the movie is over, it's established that circumstances can evolve in which no one can remain morally superior or guilt-free - and survive.

The blinded man's wife (Yoshino Kimura) takes him to an eye doctor (Mark Ruffalo), who has never encountered anything like this malady. It seems to come on with the suddenness of a virulent fever. A terrible unease soon sets in as the doc, his receptionist (Susan Coyne) and another patient (Alice Braga - of I Am Legend and Lower City - as an enterprising call girl) - all exposed to the original sufferer - come down with the whiteout malady.

The government, getting wind of the spreading blindness epidemic, rounds up all known victims and transports them to a disused warehouse where they are placed in quarantine. Once deposited in the facility, they are left to fend for themselves, with food and other supplies being shuttled in to them periodically. It seems the sighted have very little use for the blind, and (naturally) fear joining their ranks. It's a case of "out of sight, out of mind."

Except for the fact that, each day, more and more sufferers of the mystery disease are shuttled into the facility. This stretches the limits of its capacity: first beyond the bounds of comfort, and then beyond the limits of survivability. As the population of the warehouse increases, the slow accumulation of despair (and filth) inexorably mounts. Meanwhile, beyond the fenced perimeter, armed guards stand ready to shoot anyone attempting escape. We seem to have descended into an outer ring of Dante's Inferno - and we're sinking ever deeper.

But here's the twist: the good doctor's wife (Julianne Moore of Children of Men) has stowed away with her husband under the guise of herself being blind - although she is not. So the doc and everyone else in his ward have an ace in the hole in terms of day-to-day functionality, though the couple attempts keep this a secret from their forced companions.

Complicating matters further (and ramping up the despair level considerably) is the introduction into the facility of an alpha male with a defective moral compass (Gael García Bernal, great in Babel - and, again, here) who decides to make the most of this new blindness gig by kicking ass and taking charge. To expedite this agenda he enlists the aid of a man (Maury Chaykin) who's been blind all his life, and thus knows the ropes. Their chief advantage? The wing they occupy is where the food rations enter the building. And those who control the food can call the shots. (Which they proceed to do.)

How long can the residents of the doc's ward put up with the increasingly dehumanizing demands put upon them by the King of Ward Three? And what actions will they, the disenfranchised, consider in order to regain control of the food distribution process? There are, we realize, no easy solutions - though one obvious one presents itself.

Director Meirelles demonstrates his virtuosity while treading the thin line between hurling us into the pit of despair and allowing us glimpses of the nobility and resilience of humanity.

There are so many readings of this material (adapted from the José Saramago novel by screenplay author Don McKellar) that one can spend far more than the film's two-hour runtime exploring resonances. Blindness is a convenient malady for the story line, but deafness could as easily have been chosen as the epidemic's end result. Or even something more eccentric, like speaking in tongues. The point about society's fear of - and dissociation with - those of diminished capacity works regardless. At the same time, blindness is the perfect choice, because of the rich metaphorical associations (see quote, below).

Most evocative of all is the way the film ends. I'll refrain from revealing specifics - I wouldn't dream of diluting its emotional punch - but I will say this much: when you think the situation is resolved, think again.

And I mean that quite literally.