A pair of NYPD detectives in the Narcotics Bureau stumble onto a heroin smuggling ring based in Marseilles, but stopping them and capturing their leaders proves an elusive goal.

After being double-crossed and left for dead, a mysterious man named Walker single-mindedly tries to retrieve the money that was stolen from him.

William Friedkin's gritty police drama portrays two tough New York City cops trying to intercept a huge heroin shipment coming from France. An interesting contrast is established between 'Popeye' Doyle, a short-tempered alcoholic bigot who is nevertheless a hard-working and dedicated police officer, and his nemesis Alain Charnier, a suave and urbane gentleman who is nevertheless a criminal and one of the largest drug suppliers of pure heroin to North America. During the surveillance and eventual bust, Friedkin provides one of the most gripping and memorable car chase sequences ever filmed.