In his groundbreaking 1996 movie Scream, director Wes Craven — with help from Kevin Williamson’s cheeky postmodern screenplay — peeled back the mask on modern horror, revealing a set of previously unspoken rules governing the mayhem in teen slasher flicks. Among those rules to avoiding murder (“Don’t do drugs!”), perhaps the most resonant for a generation living under the specter of AIDS was this: No premarital hanky-panky. In other words, when it comes to surviving a horror movie, always remember that sex equals death.

There is very little that is postmodern about the new horror film It Follows, though writer-director David Robert Mitchell does take Craven’s “sex is death” prohibition and utterly run amok with it, creating a randy little masterpiece of post-AIDS paranoia and terror.

The set-up is as simple as the moral implications are complex: At the end of a strange, somewhat disturbing date, Jay (Maika Monroe) has steamy backseat sex with Hugh (Jake Weary), who immediately drugs her, ties her up in an abandoned building and warns her about “it” — a shape-shifting, slow-moving but persistent sexually transmitted demon that will continue to follow her until it either kills her or she fucks someone else, in turn passing it along.

Channeling such legendary filmmakers as horror master John Carpenter and, to a lesser degree, Stanley Kubrick, Mitchell employs a tinkling, almost cheesy score of synthesized music combined with gorgeous cinematography — jump cutting from anxiously airy wide-angle shots to jarring close-ups — to create an atmosphere that is at once hypnotic and unnerving.

Shot in and around Detroit, the film revels in the decayed grandeur of that former industrial powerhouse, creating a gritty realism that is heightened by a cast of young actors who, unlike the typical knuckleheads and bimbos common to most horror films, display all the unreconstructed yearning and blemished discomfort of kids on the verge of adulthood.

Because the teens seem so real and familiar — as they make fart jokes, clip their toenails and tentatively advance and retreat on each other’s cursed affections — the terror that stalks them is that much more effective, like a manifestation of their own sexual uncertainty.

And aside from all this, It Follows is just plain fun and scary, like Halloween and Nightmare on Elm Street before it. As in those classics of the genre, It Follows hones in on a tight-knit group of teens that finds itself screwed by pure evil, with enough twists and tension to keep the audience on edge until the final frame. 

It Follows opens Friday, March 27, at Bijou Metro.