What makes a “classic” film is what it leaves in the memory — sympathetic, lost or loathesome characters played by gifted actors, stunning visuals, seamless editing, a relatable or vicariously thrilling plot, pithy, quotable dialogue, or perhaps a couple of iconic scenes that burn into your psyche.

And then there’s “The Third Man,” one movie which one can confidently say has all of these elements, each of them a benchmark for measuring other films of its era and of all time against. In genre terms, it’s a mystery-thriller, one that transcends genre. In cinephile speak, it is a perfect thriller.

Director Carol Reed made other films, an Oscar winner among them. But this epoch-defining mystery-thriller was his masterpiece. Writer Graham Greene‘s stylish, naunced prose and shades-of-grey characters made his novels irresistible to filmmakers, even if his genre specialization and sheer popularity meant he’d never be more than “short listed” for the Nobel Prize for literature.

Joseph Cotten was one of the finest actors to never win an Oscar, or even a nomination. Orson Welles was brilliant in his own films, but given the greatest “star entrance” in the history of cinema, he transcends performance. His character becomes a symbol and one permanently attached to the “larger than life: Welles legend. Trevor Howard’s stiff-upper-lip British Army officer became his permanent onscreen persona after this 1949 film. But look at the shadings he gives this Major Calloway.

I’ve seen this film many times on TV, in college cinema societies and film festivals, and developed a great appreciation for its classic moments and brilliant turns of phrase — “The Cuckoo Clock” speech included — in editing snippets of the soundtrack into a long public radio celebration of it during my NPR station days.

But the truism about classic films and filmlovers is that every time we return to a great film, we stumble into details we hadn’t noticed, shadings we had not picked up on, rich textures in cinematography, editing, dialogue, characters and performance.

What stands out anew here are not just the great, underscored moments — the big scenes, the seductive pull of Austrian Anton Karas’s alternately jaunty and mournful zither music, the vast empty streets of post-conquest Vienna in the dark of night, the startling close-ups, the perfectly-turned phrases, outstanding performances and breathless, mostly music-free chase through the shadowy sewers of the ancient city.

And damned if I remembered Holly Martins’ tipsy trip to a burlesque club and the naked-save-for-pasties Viennese dancer he ignores between drinks.

But let’s notice that Reed and Greene had the simple epiphany of leaving lots of dialogue in untranslated German, reinforcing how out of his depth our “innocent” American pulp Western novelist Holly is in this alien, bombed and Nazi-corrupted city.

“Third Man” is correctly-labeled a “film noir,” but it’s a transitional tale in that regard. It recognizes the innocence with which the New World entered the Old World’s War, and lets us see that curdle in the figure of the naive, broke, dogmatic and yet doggedly determined dime novelist who thinks he can find out what really became of his old pal, a notorious racketeer run over by a car just before Holly’s arrival.

The plot — Holly Martins (Cotten) shows up, the struggling author of “The Oklahoma Kid” and “The Lone Rider of Sante Fe,” summoned to Vienna by the promise of a post-war job with his old friend Harry Lime (Welles). He arrives too late, he learns. He picks up bits of the story — in broken English — from Harry’s porter-neighbor (Paul Hörbiger).

There was an accident. Harry is “already in hell,” the old man suggests, “or in heaven.”

Holly hastens to the funeral, sees a mysterious woman (Alida Valli) there, perhaps the one genuine mourner. And he meets British Major Calloway, whom he insulting calls “Callahan” more times than the “I’m English, not Irish” Brit would like.

Harry’s death? “Best thing that ever happened to him,” the Major sniffs. Nothing for it but to find poor Holly a spot on the next flight back out.

But Holly hears conflicting versions of how Harry died. He died “instantly,” one witness says. He spoke of Holly and left instructions to meet and take care of him, says another. There were two men with him when he died. Or maybe there was a “Third Man.”

As Martins, irate at the tactless and he believes improperly judgmental Calloway, digs deeper, he meets the guarded, fearful actress Anna (Valli) and gets on Calloway’s last nerve. The major’s hulking sergeant (Bernard Lee) may be a fan of Martins’ books. But that doesn’t mean he won’t bop the foolish Yank if the need arises.

“I don’t want another murder in this case,” Calloway cautions Holly, after he’s mentioned people who have disappeared or died thanks to Harry Lime. “And you were born to be murdered.”

It’s startling, watching the film anew, how well the “mystery” of it all plays, even with repeat viewings. Audiences of the day saw Orson Welles’ name in big letters on the posters and cinema marquees. They guess who Harry Lime is, and well, if he’s really dead, how’s he going to turn up an hour into the picture?

Reed and Welles contrived to make the “Citizen Kane” star’s delayed, mysterious entrance an unforgettable jolt. We glimpse a figure, in long shot and shadow, outside the upstairs window of stage-actress Anna’s posh but faded Viennese flat. Acat who only warmed to Harry, she’s told Holly and us, goes to that shadow and licks his wingtip shoes. And we wait.

Only when Holly shouts into those shadows and a neighbor turns on a light and opens a window is Harry revealed — smirking, cocksure and elusive.

Their actual meeting is more sinister than sentimental. Harry’s out for himself and makes a decision, on the fly, that he and Holly chat in a ferris wheel car. There were few amusement park safety protocols in postwar Vienna. Holly and we figure out that Harry, like the smiling and droll cornered rat that he is, will do whatever it takes to save his skin.

Welles concocts a classic Welles speech to explain Harry’s jaded rationale for his amoral ways, one that sums up that a world war is over, the Russians and other allies are administering shellshocked Vienna with one eye cast towards the Cold War to come. America was largely spared the ruinous effects of World War II, and that feeds the country’s diehard idealism. But strife and trauma have payoffs as well as costs, Harry suggests, opening his friend’s eyes to his true self-serving nature and the cynicism that the rest of the world lives under.

“Like the fella says, in Italy for 30 years under the Borgias they had warfare, terror, murder, and bloodshed, but they produced Michelangelo, Leonardo da Vinci, and the Renaissance. In Switzerland they had brotherly love – they had 500 years of democracy and peace, and what did that produce? The cuckoo clock.”

Cotten’s folksy gentility served him well in Welles’ earliest films. But he’d already played against type for Hitchcock, as a charming serial killer in “Shadow of a Doubt.” Here, he’s a reactor — naive but getting a clue, loyal but noble, feeble but getting tougher by the moment as his underestimated outrage is engaged. The major may repeatedly attempt to brush him off, and Harry’s cadre of sketchy Viennese “friends” may lie, nudge and even threaten him.

But Holly with the sissy name is getting to the bottom of things. Maybe he’ll even write a book, he says in returning the threats.

“lt’s a murder story. l’ve just started it. lt’s based on fact.“

Valli is stoic, striking just the right note of a survivor-facing-one-last-shock and trauma.

But what really stands out among the performances on this latest viewing is the function of Howard’s Calloway, and the shades he gives the man. There’s a post-war British realization in this character that they’re always going to be depending on America’s good graces and American alliances from here on out.

Calloway is stern and tactless when talking about Lime, but he does all he can to spare Martins the details, trying to preserve his innocence just long enough to get him on a plane out of town. Proof of Harry’s crimes he saves for third act shock value. Like Churchill massaging American neutrality before Pearl Harbor, the bluff Calloway resigns himself to working Holly, winning him over, convincing him to do the right thing, preparing him for the inevitable.

The various Viennese and German actors employed in supporting roles play archetypes — never wholly innocent, even those who might be “re-educated” to repent and rejoin Western civilization. The Russians depicted here are officious and unfeeling, eager only to turn off the spigot that has Eastern Europe already fleeing to the West.

Wilfrid Hyde-White is delightful as a friendly but pretentious cultural “reeducation” attache who latches onto “author” Holly for a lecture, too well-mannered to let the shock show as he figures out just what Holly writes and how far pulp Westerns are from the fiction of James Joyce.

Lee, one of two future James Bond bosses (Geoffrey Keen plays another soldier) in the cast, brings a good-humored bulk to the fanboy sergeant who is thrilled to meet Martins, but not above following orders when Holly gets out of line.

Through all this Graham Greene intrigue and politically-astute symbolism, Reed maintains suspense, saving a scattering of jolts for the later acts. A small child, speaking only German, casts suspicion on Holly when another Viennese native dies during Holly’s hunt for what happened to Harry, an homage to a similar accusatory moment in Fritz Lang’s “M.” The days are washed-out and monochromatically dreadry. But every trip out of doors into the dark is fraught with forboding in a dimly-lit curfewed city in which no decent person would dare venture onto these streets at night.

And Harry’s escape through the sewers remains the foot chase against which all others are measured.

But for all this artistry and artifice put to use making an iconic film, the cynical edge, political prescience and sheer entertainment value here ensures us that we never lose track of the fact that “The Third Man” was and remains the brainchild of one genius above all the other brilliant people involved in realizing it.

Graham Greene had many of his works adapted for the screen, sometimes with him producing the script. Reed had 35 screen directing credits, including a couple of epics. But the cinematic highlights for both artists remain their collaborations, with “The Third Man” and “Our Man in Havana” as undisputed classics.

Welles and his pal Cotten may get outsized credit for the glories of “The Third Man.” We recognize Karas’s nervous, period-and-locale-appropriate zither score and cinematographer Robert Krasker’s startling shadowy compositions. But it is that combination of writer and the one filmmaker who really “got” Greene that makes this perfect thriller their masterpiece and this 75 year-old film essential viewing for any filmmaker, film critic or film buff to this day.

Rating: “approved,” violence, one nearly nude exotic dancer

Cast: Joseph Cotten, Alida Valli, Trevor Howard, Bernard Lee, Paul Hörbiger, Ernst Deutsch, Wilfrid Hyde-White and Orson Welles.

Credits: Directed by Carol Reed, scripted by Graham Green (Carol Reed and Orson Welles were uncredited), based on the novel by Graham Greene. A British Lion release on Tubi, Amazon, etc.

Running time: 1:44