Already a record-setter in cost vs. revenue returns, this low-budget (reportedly $15,000), independent debut film by writer/director Oren Peli – a former video game programmer – is poised to swell to phenomenon-like proportions while sending overblown splatter-core and slasher-porn movies back to school. (That includes you, Saw 2-6.) With two cameras, two main actors, a house interior and few special effects, Peli and company have injected Paranormal Activity with a booster shot of gleeful imagination and malicious cunning that not only scared the willies out of audiences at sneak previews, but should also shame big-budget horror filmmakers.

A title screen cryptically implies that San Diego police recovered the footage you’re about to see. As Katie (newcomer Katie Featherston) pulls up to the driveway of a starter tract house, her boyfriend Micah, played by unknown Micah (naturally) Sloat, is playfully shooting her on camera, a la Cloverfield. The couple banter with a naturalistic ease as the film assumes the guise of found footage/documentary. Its true documentary conceit washes away, replaced by the easy pacing of a domestic home, made more familiar by the anti-acting performances of the suburban leads. Micah keeps filming. It dawns on you that all you’re seeing are shots from his camera, which unwittingly locks you into the perspective of the couple, trapping you in their home. But as Micah keeps filming his girlfriend of three years, she gets increasingly irritated. It doesn’t help that the couple have been disturbed – especially at night – by something they can’t identify. A Peeping Tom? A ghost? A jealous former boyfriend? Micah is goofily flippant, though stubbornly attached to the idea of capturing some phenomenon on camera; Katie takes the incidents more seriously because, she reveals later to Micah, the weirdness started before they met.

At the end of the first day, Micah sets up the camera on a tripod overlooking the couple’s bed, on a low-light setting, and lets the tape roll. These quietly rolling shots seem destined to take their place in the horror canon alongside Linda Blair strapped to her bed, the shower at the Bates Motel and the stark woods of The Blair Witch Project, to which Paranormal has been compared: They are shots that will be synonymous with “scary.” The pace and tension build during each subsequent night, when the couple are asleep and the camera is recording. It’s not just Peli’s own imagination that’s in play during these simple scenes; he’s using the darkness and silence to conspire in the imagination of the audience. It’s not what’s on the screen that’s creeping us out, it’s what’s in our head.

Avoid hearing or seeing too many details before going to this supernatural throwback. Though it starts slow, unveiling details as it goes, the climax is explosive and presents a tasty mystery to ruminate on. The movie can survive, though, without its ending; the long, self-assured middle part methodically ratchets up the dread and sinks into the brain until the audience is screaming as if on cue. Monterey County audiences can cheer that it’s finally arrived, but they may be shuddering after it’s left the screen and keeps haunting the mind.

PARANORMAL ACTIVITY (3½) Directed by Oren Peli • Starring Katie Featherston, Micah Sloat • Rated R • 99 min • At Century Cinemas Del Monte, Maya Cinemas and Northridge Cinemas.