Carol Reed and Graham Greene’s masterpiece, “The Third Man,” opened in London in 1949 and came to New York early the next year in a version butchered by its American distributor, David O. Selznick. He sheared anti-Americanisms and other passages that he thought too European or mature or cynical or something for those of us living on what one character calls “the other side.” During the next 40 years, the print quality declined with endlessly compromised television airings. But none of this had any effect on its standing as one of the best-loved and most admired pictures ever made.

“The Third Man” has been a perennial favorite on the home video front, especially since Criterion presented its stunning 1999 restoration of the film as produced by Alexander Korda. Today, Criterion is releasing a two-disc edition The print is visually the same though the audio track has been juiced. The supplementary material, however, is generous if uneven (the commentaries are below standard) and the packaging is much improved; it no longer depicts Orson Welles on the cover, a ploy that exacerbated a phony controversy about the film’s authorship and gave away the plot — as will this review, incidentally.

I point this out in recognition that not everyone has seen “The Third Man,” though it is often thought of as one of those cultural phenomena that, like “Hamlet” or Beethoven’s Fifth Symphony, is hard-wired into our DNA. Newcomers ought to have the pleasure of credulously following the murder investigation and Holly Martins’s astonishment when, as Greene writes in his novella, “a window curtain was drawn petulantly back by some sleeper he had awakened and the light fell straight across the narrow street and lit up the features of … ” Well, you know very well whose features are lit up, which is why everyone should see “The Third Man” before the age of 12.

Set in Vienna in 1947, the film is a thrilling contradiction. Misery and horrific crimes go cheek by jowl with inspired comedy and Anton Karas’s buoyant zither music — which made him the most successful Austrian composer since Strauss. “The Third Man” is often described as perfect, which seems fair. Greene’s script, improved by Reed, who devised the unforgettable closing shot, is Aristotle-pure; even throwaway lines (and there aren’t many) reveal increasing significance on repeated viewings. Robert Krasker’s photography, coached by Reed’s blueprint for off-kilter angles, continues to astonish. Vincent Korda’s set design complements the bombed exteriors and personalities of the characters — counterintuitively in the case of Harry Lime, whose bedroom is quite feminine with its delicate fixtures, vanity table, and quilt.

Beyond the stars, consider how many frissons are triggered by the supporting cast. Whatever else it is, “The Third Man” is a supreme gangster film, and there is no stranger motley than the Lime gang. Ernst Deutsch’s Kurtz has the face of a marionette: droopy-eyed or crinkly and slit-mouthed. Sigfried Breuer’s slicked-hair dandy, Popescu, shifts mid-sentence from cavalier to murderous. Erich Ponto’s aged Dr. Winkel peers at Holly through a mirror, stepping forward ominously to correct the pronunciation of his name. Each delivers reverberant line readings, sometimes just a word — “Advice,” “Keep ze pack,” “Viiink-el.”

Paul Hoerbiger, a veteran Austrian film star, spoke no English and learned his lines phonetically. He appears to fumble his way through them while muttering in German and sustaining masterly comic timing. “Dere vas a turd man” — cue zither! Bernard Lee triggers is sublimely droll as Holly’s devoted reader, socking him with one hand and picking him up with the other. Confiscating love letters, he tells a distraught Anna, “That’s all right, Miss. We’re used to it, like doctors.”

Wilfred Hyde-White constantly leads by the elbow a silently annoyed mistress. Herbert Halbik, who never acted again, raises holy terror as Hansl, the little boy with banshee voice. And so forth, down to the smallest role. When Anna is arrested, the Soviets are accompanied by one member of the other governing forces: the American is embarrassed, the Brit admits he doesn’t know what “protocol” means, the Frenchman reminds Anna not to forget her lipstick. Lee Strassberg is said to be in this scene, but I can’t spot him.

The film is always referred to, unfairly, as an Orson Welles vehicle. True, he has the two most memorable speeches. He wrote one (with a cuckoo clock punchline) and took credit for the other (about dots on the carnival midway, written by Greene), and his charisma was never exploited more ingeniously than in his sensational, silent entrance — not even in his own films. Yet the tension is ratcheted for an hour before his arrival by Trevor Howard’s understatement, Alida Valli’s unglamorous despondency, and Joseph Cotten superbly clueless Holly, a performance measured in nuance and delicious wit. .

Holly represents Greene’s first evisceration of the “quiet American,” the well-meaning innocent abroad, whose drunken arrogance embarrasses Anna, whose bumbling leads directly to the murder of the porter, whose fate it is to kill “the best friend I ever had.” The one theme that emerges throughout the story is betrayal — in an era of informers, “The Third Man” is rife with what Holly calls “dumb decoy ducks.” Harry once persuaded Anna to betray one of his associates, and Holly is persuaded to do as much to Harry — but only after two lessons in villainy. The first, purely evidentiary, isn’t enough; like most of the world, Holly lacks the empathy to imagine suffering until forced to look at it.

Holly is given a moral pass by many commentators, including those connected with this DVD, who consider his execution of Harry a mercy killing. I think Reed and Greene had another paradigm in mind: the worm turns. By the time Holly gets to hold a gun on his friend, he has been trying to exorcise his memory for some time. He is the perennial schoolboy dupe, awed by a magnetic leader who knows how to do things, who makes life exciting, who has the kind of head for which homburgs were invented. Before leaving for Europe, Harry left Holly holding the bag and stole his girl. Yet even with Harry presumed dead, Holly can’t return the favor. Dead Harry is more vivid to Anna than living Holly. She advises him to find a girl, as though he were a harmless adolescent. Harmless he is not.

Like the hero in one of his Westerns, Holly is out for revenge, first against the major for libeling his pal, and then against his pal. Harry, bleeding and cowering like a wounded cub, may nod for Holly to put him out of his misery, but the film is more ambivalent about betrayal. Like Anna, it leaves him in the cemetery alone, to contemplate his own motives.

Morality in “The Third Man” is very public-school British, very Greene-ish, very E. M. Forster saying he hoped he would have the courage to betray his country rather than a friend. The opening Flaubertian narration (recited by Reed) lays it out. Like the start of “Madame Bovary,” it suggests that we are in the hands of a narrator relevant to the story. Yet apart from being a former smuggler, the narrator is immediately dispensed with, an anonymous figure retelling an anecdote he may or may not know firsthand. As in “Bovary,” the effect is to go from outside to inside, from bemused indifference to unspeakable horror.

Even Greene, however, must have been astonished by the topsy-turvy morality with which the world greeted “The Third Man.” Harry Lime, who murders children by stealing and diluting penicillin, charmed the audience as relentlessly as he did Anna. He returned in a radio series (starring Welles) and a television series (starring Michael Rennie), as an admirable rogue who ultimately does the right thing. The sequels are forgotten. The original is, at 58 years and counting, ageless.

Mr. Giddins’s most recent book, “Natural Selection: Gary Giddins on Comedy, Film, Music, and Books,” is available from Oxford University Press.