Based on a 1970 novel of the same name by Gerald Walker, Cruising is set in the New York's pre-AIDS S&M gay scene.
For the day, quite confronting and at times with its lurid sprays of blood showing the apparent influence of the Italian "giallo", Philadelphia this is not. A goodly portion of the film is given over to recreating the transgressive netherworld of what appears to be a latter-day Sodom, so to speak, and Gomorrah of leather and denim clad dudes indulging in random hard sex in subterranean caverns and Central Park at night as New York City apprentice detective, Steve Burns (Al Pacino), goes undercover to entrap a serial killer targeting men of a certain physical type of which he, Steve, is an examplar.
Although ostensibly a crime thriller Cruising is more a study of the central character as, typical of many 70s films, we are taken on a journey into the dark recesses of our socially-conditioned polymorphous perversity, At the outset Steve is a conventional heterosexual with a similarly-disposed girlfriend (Karen Allen) but under the influence of the unbridled male-to-male coupling that he witnesses on a nightly basis his unconsciously constructed sexual identity soon begins the crack at the seams of his leather trousers. The film is strong in the basic hetero/homo division but less credible when coming (is that going too far?) to the sadism aspect, Steve seemingly acquiring a taste for rough sex with little need for acclimatization, culminating in a suggestively twisted ending that the film doesn't bother to justify.
Friedkin is less interested in the crime thriller aspects (which were based on actual murders that took place between 1962 and 1979) treating the killer as a kind of symbolic composite whose actions are cavalierly rationalized with some kind of father-issue derived schizophrenia and whose entrapment is brought off with surprising ease if not outright complicity on the part of the killer.
Although at times his Village People dress-up is little undermining, Pacino gives a committed performance, that, for not necessarily the right reasons, belongs on the shortlist of his screen business while Friedkin keep the story moving forward energetically even if this is at the price of real depth.