In the continuing saga of the Corleone crime family, a young Vito Corleone grows up in Sicily and in 1910s New York. In the 1950s, Michael Corleone attempts to expand the family business into Las Vegas, Hollywood and Cuba.
A group of working-class friends decides to enlist in the Army during the Vietnam War and finds it to be hellish chaos — not the noble venture they imagined. Before they left, Steven married his pregnant girlfriend — and Michael and Nick were in love with the same woman. But all three are different men upon their return.
Surveillance expert Harry Caul is hired by a mysterious client’s brusque aide to tail a young couple. Tracking the pair through San Francisco’s Union Square, Caul and his associate Stan manage to record a cryptic conversation between them. Tormented by memories of a previous case that ended badly, Caul becomes obsessed with the resulting tape, trying to determine if the couple are in danger.