If The Godfather (1972) and Apocalypse Now (1979) are Francis Ford Coppola’s operas – full-blown epic operas – The Conversation is his chamber piece: intimate, elegant, scaled down. It’s a chorus of distant voices captured on hidden microphones by men obsessed with secrecy and distrust. It’s a formal, stately production, European in pace, and the least appreciated film in Coppola’s incomparable ’70s ouevre.

Seven years after he burst onto the screen as the wildly exuberant Buck Barrow in Bonnie and Clyde (1967), Gene Hackman reappears as Barrow’s opposite. Harry Caul is a professional wiretapper, a man who listens in on the lives of others because he is unable to respond to his own. He’s a figure out of Kafka by way of Watergate: his job is to blend into crowds so he can record their conversations, their secrets and lies. He wears a shapeless gray raincoat, rides a bus to work, lives alone in a nearly empty apartment. He is so closed in he refuses to tell his mistress (Terri Garr) what he does for a living. More than once he claims, even while he’s using it, that he doesn’t own a phone.

In the intricate passage that opens the movie, Harry is hired by a mysterious tycoon known only as The Director (Robert Duvall) to eavesdrop on a young couple (Frederick Forrest and Cindy Williams) as they stroll through a crowded square in downtown San Francisco in the middle of the day.

Later, when Harry edits his tapes, Coppola pays homage to Blow-Up (1966), Michaelangelo Antonioni’s own intriguing meditation on the invasion of privacy in modern times. Just as the photographer in that movie discovers, by blowing up one of his photographs, a possible murder, so Hackman uncovers its aural equivalent on one of his tapes. Replaying that sequence over and over, Hackman grows distraught, paralyzed by the idea that The Director will use his evidence as an excuse to kill the young couple. There are hints that one of Hackman’s past endeavors resulted in the deaths of three innocent people, and now he fears a repeat. Racked by guilt, Harry stumbles into a church to confess his sins and to beg forgiveness, only to flee in shame before the priest is able to offer absolution.

If Hackman represents the faceless men who walk among us with hidden wires, he also mirrors his famous director. Harry splicing tape is Coppola (and his legendary sound editor Walter Murch) splicing the soundtrack we, the audience, now listen to. While Harry replays certain segments of the couple’s conversation, Coppola shows the same couple, from various camera angles, saying those words. Hitchcock once remarked that every moviegoer is, at heart, a voyeur, and The Conversation proves his point. We too, hearing those snippets of conversation, share Hackman’s illicit thrill.

Fittingly, in the year of Watergate, Coppola’s narrative hinges on subterfuge and deceit, a startling betrayal revealed at the end of the film. Every major player is defined by paranoia. Hackman protects his apartment with a series of locks suitable to a bank vault. At a trade show a sleazy competitor (Allen Garfield) slips a ball-point pen, which is actually a microphone, into Harry’s pocket. When Hackman is seduced by one of Garfield’s employees (Elizabeth MacRae), he wakes the next morning to find that she has stolen his tapes. In Harry Caul’s world duplicity and betrayal are not aberrations, they’re facts of life.

After attending the trade show, Hackman and his colleagues (you can’t call them friends, because Harry doesn’t have any friends) gather at his shop for a party. Drinks are served, stories are told, and for a brief period the movies loses its narrative drive. Perhaps because the first third of the film is so trim and efficient, the middle section suffers. Hackman’s seduction, in particular, is clumsily enacted. Then Harry falls asleep only to be haunted by a dream, and the movie regains the rhythm – the sense of dread – it established at the start. In the dream sequence Hackman relates (to Williams) an incident from his childhood, and for the first time Harry seems fully human. Not surprisingly, he is able to reveal himself only while unconscious to someone he doesn’t even know.

Hammy, contrived, show-stopping roles (Nicholson in As Good As It Gets, for instance, or Hoffman in Rain Man) may win awards, but it’s portrayals like Harry Caul – subtle, complex portrayals – that best measure an actor’s skills. Playing a man living in an emotional vacuum requires shadings of character only a consummate craftsman like Hackman could possibly achieve. Near the end of the movie Harry cowers in a hotel room adjoining the one where he fears an act of violence – an act he considers himself morally complicit in – is about to occur. When he hears a scream, Harry collapses on the bed and pulls a blanket over his head, trying to drown out the sounds he has tapped the walls to listen to. It’s a terrifying, unsettling, pathetic moment, and it says everything there is to say about the life of Harry Caul.

In last year’s stylish thriller Dirty Pretty Things, a hotel clerk discovers, in a toilet, a human heart. Three decades earlier Harry stares in horror as a curtain of blood spills from another hotel commode. The nightmare has come true. And then, in a brilliant final twist, Coppola reveals that the corpse is not the one we expected. Once again the firm ground of reality has shifted under Harry’s feet. The voice on the tape repeats a familiar phrase, only now those words are fraught with an opposite meaning.

At the end, Harry Caul is alone. His phone rings and a voice says ‘we’re listening’. This is the new world order, the next logical step in the progression of paranoia. The walls harbor microphones, and the hunter has become the prey.