In the middle of a hot New York summer, male body parts start showing up in the Hudson River. The police suspect it is the work of a serial killer who is picking up homosexual men at West Village bars then taking them to cheap rooming houses or motels, tying them up, and stabbing them to death. Officer Steve Burns (Al Pacino who has never looked hotter than when he is in his full leathers) resembles the victims’ dark-haired, slim figure image. He’s sent deep undercover by Captain Edelson (Paul Sorvino).
Burns enters the urban world of gay S&M and leather bars in the Meatpacking District in order to track down the killer. He rents an apartment in the area and befriends a neighbour, Ted Bailey a struggling young gay playwright who does tech support to pay the bills. Burns’ undercover work takes a toll on his relationship with girlfriend Nancy (Karen Allen), due to his developing friendship with Ted and his refusal to give her details of his current assignment. Ted himself is having relationship problems with his jealous and overbearing dancer boyfriend Gregory.
Burns mistakenly compels the police to interrogate a waiter, Skip Lee. He is intimidated and beaten to coerce a confession before the police discover Lee’s fingerprints don’t match the killers. Burns is disturbed by the police brutality, telling Captain Edelson he didn’t agree to go undercover so that they can arrest someone just because they are gay. Exhausted by his undercover assignment, Burns is close to quitting, but Edelson convinces him to continue with the investigation.
Following a new lead, Burns investigates students at Columbia University who studied with one of the previous victims, a college professor. At the film’s conclusion, Burns thinks that he has found the serial killer, who turns out to be a gay music graduate student who attacks him with a knife in Morningside Park. Burns brings the man into custody. Shortly afterward, the mutilated body of his neighbour Ted is found. The police dismiss the murder as a lovers’ quarrel turned violent, and put out an arrest warrant for Gregory. Burns had earlier fought with Gregory over his relationship with Ted.
With the police under the impression that the murders have been solved, Burns moves back in with Nancy. In an ambiguous finale, Burns begins shaving his beard in the bathroom while Nancy secretly inspects the clothes that he left on a chair: a leather peaked cap, aviator frames, and a leather jacket that all look very similar to the outfit the killer wore. Burns, meanwhile, wipes off his shaving cream and looks directly at the camera. Has Al Pacino’s character turned gay, is he now into BDSM, does he like taking 12-inches of man meat up the ass? And is he the killer? Has he become a killer or were there others in the gay bars all along?