Al Pacino puts in a brilliant Oscar-nominated performance as Frank Serpico, an idealistic, young New York police officer who discovers corruption is rife among his fellow officers. Eventually Serpico goes undercover to expose the corruption after being pushed to the brink, initially by his colleagues' distrust and later by the threats and intimidation they level against him.
Based on a true story and released in 1973, Sidney Lumet's powerful police thriller is a gem. Pacino rarely bettered this performance. Highly recommended.