Frank Serpico is an honest cop in the NYPD and is therefore not only lonely but also dangerous.
In 1973,after the disenchanted, psychotic cops of The French Connection and Dirty Harry, Al Pacino's Frank Serpico came as a paradoxical change of pace. Despite his hairy hippie disguises and rebel attitudes, he was in fact a throwback to the Dixon Of Dock Green/Dragnet image of cop as paragon of personal integrity and social justice. Sidney Lumet's film, however, is the ultimate development of the all-cops-are-bent theme that understandably proliferated in the counterculture-dominated, post-Watergate 1970s.
The real Serpico was a New York 'tec whose contribution to fighting crime was not in action against the underworld, but in testifying against police corruption, thus making himself very unpopular with the rest of the boys in blue. Lumet opens with an edgy suspense sequence that winds up with the hero gunned down in the line of duty, and the suggestion that his own department has colluded with the mob to have him shot. He then adopts a straggling, biopic approach, flashing back through Serpico's career.
We see the hero develop from a naive rookie who refuses even to accept free meals from restaurateurs on his beat, through a period as a hot-dog undercover man, into his lonely crusade against the NYPD. Pacino interestingly makes Serpico a misfit, his inability to sustain relationships and semi-vigilante street tactics suggesting that sheer bloody mindedness might have as much to do with his stand as idealism. Finally, the hero is an isolated, broken man who retires to Switzerland with his only faithful friend, an equally shaggy dog. It's no great victory, but it is great.
Al Pacino delivers a powerful performance in this compelling biopic...of a cop and a city's police force.