A hotshot Washington criminal lawyer becomes the target of a rogue security executive videotaped in the act of murdering a congressman when the incriminating tape is surreptitiously slipped into his shopping bag by the videographer, who is fleeing the executive's assassins.
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.
New York City detective Daniel Ciello agrees to help the United States Department of Justice help eliminate corruption in the police department, as long as he will not have to turn in any close friends. In doing so, Ciello uncovers a conspiracy within the force to smuggle drugs to street informants