Taking the "so bizarre it might be true" premise from The Texas Chainsaw Massacre to its natural conclusion, the much buzzed-about Blair Witch Project cleverly blurs the line between fact and fiction to the point that many audiences can't be sure that there isn't some grain of truth to the whole thing.

Something about Chainsaw, with its low-budget grittiness and creepy truth-is-stranger-than-fiction detail (who can forget the skeletal creations in Leatherface's storeroom?), transforms the experience from what is clearly a reenactment of a fictionalized murder spree into a frighteningly real fright show in which the viewer seems somehow caught up in the melée.

Passing itself off as the real deal, the refreshingly original Blair Witch Project presents its terrors as actual footage left behind by three student filmmakers who disappeared in the woods while filming a documentary.

The Blair Witch Project is one of those rare great ideas in filmmaking, a concept with such potential it's amazing no one had tried it before. Yet the novelty of the premise only makes the fact that it doesn't quite achieve what it sets out to do all the more maddening. After Blair, no one can make a film that exploits our willingness to believe a first-person horror story without drawing parallels. Still, the idea could certainly be improved and provides the perfect foundation for up-and-coming filmmakers to show what they can do at minimal expense.

The film relies almost entirely on the power of our imaginations to fill those details that are missing. The atmosphere is intense, but the chills only come indirectly. Depending on your ability to fill in the missing details, the mere suggestion of an evil force that pulls teeth from your companion's head and leaves them for you to find can be far more menacing than any disfigured, gore-dripping goon shown on-screen.

But there's almost more to annoy audiences with The Blair Witch Project than there is to enthrall them if they haven't done their research. Daniel Myrick and Eduardo Sánchez, whose idea Blair was, came up with something revolutionary enough to win over weary festivalgoers at Sundance and Cannes where it's not so irksome to watch a film shot unsteadily on black-and-white 16mm and color video.

But when it comes to a wide theatrical release, Blair doesn't go quite far enough to justify the avid rumors that it might be the scariest film ever. In a move that further proves their ingenuity, Myrick and Sánchez discovered a way to translate the festival darling into a cultural phenomenon.

The duo took to the internet, embellishing the Blair Witch legend and further obscuring the mystery of the three lost film students. Their project evolved into a pseudo-documentary airing this month and next on the Sci-Fi Channel, an hour-long program so clever it almost outdoes the film its hyping.

One of the characters interviewed by the student filmmakers at the beginning of Blair recalls a special she had seen on the Discovery Channel or another such cable network, something about the legends of Maryland. Curse of the Blair Witch, the Sci-Fi documentary, presents itself as a similar program, picking up the Blair Witch legend after the disappearance of the three kids.

A brilliant publicity coup, Curse passes itself off as one of those so-bored-you-might-almost-tune-in hour-long cable specials. The gimmick: audiences desperate to know more about Blair will seek this one out, hopefully before seeing the actual film in theaters.

Completed long after The Blair Witch Project, Curse provides all the backstory viewers need to appreciate the finished film: character development on the three filmmakers, history and folklore on the Blair Witch and tantalizing tidbits from the film that will have them salivating for the feature.

Curse actually leaves the majority of such cable documentaries far behind, weaving together interviews and manufactured evidence against a backdrop of sound effects and visual touches reminiscent of Chris Carter's Millenium devilry. Starting from nothing, Myrick and Sánchez have molded a new urban legend. From the confused postings on bulletin boards across the internet, its clear that many eager viewers are buying the story hook, line and sinker.

One of the best touches in the show, which mixes opinions from sources as diverse as a swinging '70s witch stud to testimony given by a killer working at the beck of the Blair Witch, is the inclusion of cynical dissension from a local college professor. Myrick and Sánchez have grown comfortable enough with their own legend that they can call its validity into question.

The only thing that seems to be missing from the Curse of the Blair Witch documentary is the dramatic reenactment that seems to be an inevitable ingredient of Unsolved Mysteries and other cable programs that peddle similar fare. Of course, the point is not to give away the ending of the film, but a hokey "what might have happened" scenario would have given the special that last fiendish twist it needs.

Not only does Curse establish the essential backstory to the film, but it lets you know exactly what to expect. Nowhere in The Blair Witch Project do the filmmakers suggest that the film will lead to an ambiguous and inconclusively abrupt ending, and the film's anti-climax seems to disappoint college audiences expecting the film to get scary in some conventional sense.

As Sheriff Ronald Cravens explains in Curse of the Blair Witch, "I reviewed the film, and all I found was the students themselves, some scary noises in the woods that night (and a few examples of that), but no concrete evidence on what happened to the students."

And that's all audiences are going to get from Blair. The snippets of legend that appear in the film play a whole lot spookier if you already know about the most sinister details. After all, who's afraid of a witch? You opinion might change if you believe that dogs teeth grow from her legs, that she could be responsible for a disemboweled search party and a gruesome slew of child murders.

Seeing The Blair Witch Project by itself feels like watching Neil Armstrong's moon landing without understanding why a man in an oversized white outfit might want to plod around on a stretch of mysterious pockmarked terrain. Tracking down Curse of the Blair Witch or exploring one of the movie's Web sites (the two official sites are located at www.blairwitch.com and www.haxan.com/blairwitch) before seeing the film in theaters will give you the full experience, one that promises to be as frightening as your imagination can make it.