Real life story of undercover police officer Frank Serpico (Al Pacino), who discovers that corruption is rife soon after joining the force. Refusing the payoffs which have become accepted practice, the nonconformist Serpico finds himself spurned and harrassed by his fellow officers. When the strain of performing his job honestly finally becomes too much, Serpico turns first to the disinterested police commission and finally to the 'New York Times' to make his voice heard, and is forced to give evidence in the resulting investigation. However, with the cops as well as the crooks now out for his blood, Serpico discovers that integrity comes at a very high price.