This may be the best Seventies paranoia film, chock full of astounding actors: Gene Hackman, John Cazale, Frederic Forest, Cindy Williams, Teri Gar, Harrison Ford, Robert Duvall, and others. This was written and directed in 1974 by Francis Ford Coppola, and Coppola and his actors were at the height of their talents.
Hackman plays Harry Caul, a surveillance expert who has caused the death of at least one innocent person and may be on the threshold of the deaths of other innocents. Or maybe not. He's so paranoid, who can tell? Forest and Williams play a young couple who walk around Union Square in San Francisco and have puzzling conversations that only Caul can arrange to surveil. Are they going to be murdered? Or are they just lovers on a lunch break?
Hackman gives Caul a soul-wrenching angst that lifts "The Conversation" out of the run of the mill genre like "Three Days of the Condor" and "Night Moves," another Gene Hackman movie. John Cazale, Teri Garr, and Harrison Ford make major contributions to the film, as well.
The technology, of course, is horribly dated, but this is a character- and paranoia-driven movie, so I'm happy to overlook the equipment.
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The key to the film is what the couple means when they make a particular statement, which Caul has recorded. Caul listens to it over and over trying to parse it out, but the problem with the film is that Coppola had the statement re-recorded by the actors with different emphases to create the confusion Coppola needs for Caul to feel, instead of having an ambiguous reading of the line to begin with. The meaning changes drastically from our first hearing of the statement to the last because the way the line is said changes drastically. It totally turns the movie around.