In the opening shot of Francis Ford Coppola’s The Conversation – one of the great opening shots in cinema – a slow, telescopic zoom scans the lunchtime crowd on a sunny day in San Francisco’s Union Square. As if by accident, the camera settles on Harry Caul (Gene Hackman), a middle-aged man in a grey raincoat whom we may not have even noticed if it weren’t for a busking mime sidling over and beginning to mimic his movements. Harry walks off. The mime follows, trying to mine more material from his gait, but quickly grows bored and gives up. Right from the start, Harry Caul is apparently so unmemorable, so thoroughly nondescript, that he seems immune to parody.

This is by design: Harry is an expert at blending in, on this particular day and in life in general. A freelance wiretapper, or ‘bugger’ – though Harry would no doubt prefer the term ‘surveillance and security technician’ – he is currently tailing a young couple (Cindy Williams and Frederic Forrest), who appear to be having an affair. Three of Harry’s men (including Stan, played by the great John Cazale) are listening in as well: one in the back of a van, one embedded in the crowd, and one planted on a distant rooftop, toting a directional microphone with a sniper scope (state-of-the-art surveillance technology for 1974). Harry passes shoulder-to-shoulder with the couple and goes unnoticed; he is an anonymous man in a grey raincoat moving through a grey city, perfectly camouflaged – a consummate professional. But once Harry returns to his workshop and combines the multiple audio recordings into one perfect mix of the titular conversation, the contents of that private discussion – and its importance to Harry’s mysterious employers – will begin to tug at a conscience he has made a living by suppressing, jeopardising a life built on the same kind of secrecy he so diligently denies others.

The Conversation premièred at Cannes in 1974, a mere eighteen months after the release of The Godfather. Coppola would round out the decade with The Godfather Part II (1974) and Apocalypse Now (1979), an all-time directorial winning streak that would end in 1981 with the lavish non-starter One from the Heart. Fifty years on, newly restored, and heading back to theatres at the same time as Coppola’s latest release, Megalopolis, The Conversation feels like an outlier in his early repertoire for its intimate scale and focus, cramming all of its director’s operatic morality into one lonely man’s head. It remains a masterpiece of tone and tension, one that sticks to your ribs long after you first see it, whether that was yesterday or half a century ago. In a historical sense, it functions as a bridge between the Hollywood noirs of the 1940s and 1950s and the paranoid thrillers of the 1970s and 1980s. Even though the script had been completed in the mid-1960s, The Conversation was released during the thick of the Watergate wiretapping scandal, placing it in the vanguard of a new type of movie exploring Americans’ rapidly eroding trust in their institutions.

Francis Ford Coppola filming in the Palazzo Margherita (photograph by Rich Cohen)

The Conversation starts off as pure procedural thriller, with Harry Caul its classic gumshoe; his is a dirty line of work, but he brings what dignity he can to it. He is brilliant and methodical, bordering on monastic, and has no intention of patenting or franchising out any of his own inventions for a quick buck. This puts him in stark contrast to Bernie Moran (Allen Garfield) and the other hangers-on that Harry brings back to his workshop for a party after a surveillance tech convention, where Bernie has been selling, among other things, a harmonica-activated phone-tapping device (‘It’s junk,’ Harry tells Stan). Of course, Harry and Bernie are more similar than Harry would like to admit. They both make a living and presumably sleep at night, thanks to the age-old, all-American dictum of a man just doing his job. When Stan presses Harry on the meaning of the conversation between the couple in Union Square, suggesting that it’s only human nature to be curious about the people they listen in on, Harry stonewalls him: ‘If there’s one sure-fire rule that I have learned in this business, it’s that I don’t know anything about human nature. I don’t know anything about curiosity. That’s not part of what I do.’ Of course, this particular conversation – the one that infiltrates Harry’s dreams and haunts the whole movie through Walter Murch’s extraordinary sound design – proves the exception to the rule.

In a career filled with culture-defining performances, this is one of Hackman’s best. His Harry Caul is a man of extreme yet relatable contradictions: he longs to be invisible, yet craves the approval and celebrity granted by his industry colleagues; he yearns for connection, yet treats his co-workers as worthless subordinates; he communicates only via payphone and has never told his girlfriend a single personal detail, yet willingly enters a confession booth and spills his sins before God.

One of The Conversation’s greatest accomplishments is how fully Harry’s internal conflicts feel reflected – often literally – in the film’s textural style and scenery. Coppola and cinematographer Bill Butler surround Harry with frosted glass, coloured perspex, reflections of steel and neon, even that flimsy grey raincoat, making The Conversation a film of murky translucence – solid yet see-through – and its hero a ghost trapped between worlds, between his hard-won skills and his Catholic guilt. What makes Harry such a timeless and tragic figure (as well as such a useful tool to his employers) is that, at the end of the day, he’s bound to revert to his essential nature: that of a button man, a willing stooge to a faceless master. No matter how many times Harry throws away his pay packet in a fit of righteous anger, he will always stoop down to pick it up again.

For all their prescience, one thing the paranoid thrillers of the 1970s couldn’t predict – how could they? – was just how complicit we would be, fifty years later, in the dismantling of our own privacy, or how quickly and eagerly we would trade in our secrets for the sake of convenience. What films like The Conversation did predict, with frightening accuracy, was the advent of human interaction as sellable data, and the reduction of meaningful conversation to a lopsided information exchange: eavesdropping on strangers, staring into a one-way mirror and expecting some sense of connection. These films also predicted the ongoing utility of men like Harry Caul – men just doing their jobs – and their willingness to maintain the moral deniability of one good, blind eye. Even in the digital age, the flow of sensitive information and its attendant power and wealth require the handiwork of those immune, or at least inured, to that information’s actual meaning: those who can’t (or simply won’t) hear the subtle difference in intonation between ‘He’d kill us if he got the chance,’ and ‘He’d kill us if he got the chance.’