Celebrating the 27th anniversary of William Friedkin’s “Cruising” feels like celebrating the day after your son joins a cult. It’s a weird date to pick to celebrate something that doesn’t automatically put you in a jubilant mood. This year also sees the 27th anniversary of many movies that don’t feature public sex, poppers, slings, and extreme nipple tweaking, but Warner Home Video has chosen instead to re-release a newly restored print of “Cruising” followed by a special edition DVD. “Cruising” tanked at the box office and it’s generally regarded as politically insensitive trash, remembered mostly because it’s where horrified teenaged boys first discovered exactly what an adult male could do, given enough Crisco.

Shot in New York City in 1980, and vigorously protested at the time, “Cruising” is an under-plotted slice of urban dread about a serial slasher stalking the city’s gay, leather community. Paul Sorvino plays a dead-eyed police captain who tosses rookie patrolman Al Pacino out on the streets as undercover bait because he happens to resemble three corpses found bobbing in the harbor. Mr. Pacino refashions himself into a leather boy and starts hanging out in meatpacking district bars such as the Ramrod and the Manhole where, drowning in an ocean of man sweat, he tries to track down the killer, in the process turning more than a little violently homophobic himself. A couple of last-reel coincidences slam the lid on this untidy plot and it ends in an ambiguous haze.

In the early ’80s, having a mainstream slasher flick set in the kinkiest realm of gay life was agonizing for the queer movement whose unofficial motto at the time was “We’re just like you!” Protested and reviled, “Cruising” doesn’t even have the saving grace of being very good. Mr. Friedkin had done homosexual themes before with “The Boys in the Band,” he’d done horror with “The Exorcist,” and he’d done New York with “The French Connection.” If practice indeed makes perfect, “Cruising” should have been astounding and, for the first hour, it is. But then the wheels of the plot creak into motion and the energy drains out of the picture as knotty sexual ambiguity is replaced by pedestrian gore.

We’re left with half of a good film, and it’s good because in his quest for authenticity, Mr. Friedkin has built a time machine that takes us back to a more elemental, less user-friendly New York. It’s a mythical city where the Central Park Ramble is a garden of sexual delights, and the meatpacking district is full of adults in crowded clubs getting exactly the kind of sex they want, rather than full of little children in Cielo ordering $500 bottles of vodka.

With over 72,000 AIDS deaths in New York to date, it stands to reason that a large slice of the men you see in the club scenes are no longer with us. But here in their disco grottoes, behind their mustaches and muttonchops and leather, behind their tough-guy masks, they’re smiling. They’ve found a place in the world where everything finally makes sense. Putting the serial-killer portion of the movie aside, Mr. Friedkin has made a movie about people having fun. It’s touching and it’s sweet, all the more so because, outside of “Cruising,” it’s lost forever.