The truly frightening darkness connected with Jonathan Liebesman’s debut feature is when the house lights dim and this truly wretched excuse for a thriller starts up; what follows is one-and-a- quarter hours of sheer cinematic offal. “Darkness Falls” is nothing more than a chaotic jumble of horror movie tropes, both visual and auditory–figures that persistently jump into the frame, loud noises, screeching music cues, jumpy camera moves, on-and-off lighting, maniacally propulsive music–that in the final analysis add up to next to nothing. The basic problem is that, despite a full five minutes of pre-credits exposition (via still photos and arch narration) to explain the cause of the terror that supposedly afflicts the titular Maine town–background that comes across, to be sure, as totally ludicrous–the script promptly ignores all the “rules” when the plot actually kicks in; anything goes for the sake of one more shock. For a horror picture to violate its own premises, as silly as they might be, in a search for cheap thrills is a sign of utter desperation, and that’s what distinguishes this picture from something like “A Nightmare on Elm Street,” which might have been implausible on its face but at least played fair on its own terms.

The back-story of “Darkness Falls” is that in the mid-nineteenth century, a kindly old widow whose face had been disfigured in a fire (and who thus wore a porcelain mask) was nicknamed the Tooth Fairy for her habit of giving local children treats in exchange for their baby teeth. Unhappily, she was falsely charged in the disappearance of two youngsters and hanged before the wayward kids reappeared. Since then, we’re told, the woman has haunted the town as an angry ghost, preying on children who’ve just lost their last baby tooth and “peek” to glimpse the Tooth Fairy when she shows up to replace it with money. In a prologue we see an adolescent boy named Kyle (Joshua Anderson) threatened by the old biddy one night, and his mother (Rebecca McCauley) killed in the process–a death for which the kid is blamed and institutionalized. Twelve years later, Caitlin (Emma Caulfield), once the object of Kyle’s puppy love, contacts the still-troubled fellow (now played by Chaney Kley) for help with her brother Michael (Lee Cormie), a tyke who’s suffering from the same syndrome that had plagued Kyle: he’s terrified of the dark and won’t sleep for fear of being gobbled up by the Tooth Fairy. Kyle returns home, to hostility from most of the townspeople, and before long he, Caitlin and Michael are fleeing the spirit who, now seemingly unleashed and following no pattern whatever, appears intent on slaughtering everyone in sight, baby teeth or no. Much is made about how she can operate only in the dark, which leads to lots of calls for flashlights and electrical power, and it will hardly come as a surprise that the local lighthouse features prominently in the elaborate finale. But by that time all rhyme and reason have flown out the window and mediocre special effects have taken over with–if you’ll permit the pun–a vengeance.

Even in such a summary the plot is a mess–if the real TF (you can see him in “The Santa Clause 2”) had anything to say about it, he’d probably sue for slander. Much of the action is clumsily staged by Liebesman in shadow and gloom, which makes it inordinately difficult to discern what’s going on; but that doesn’t matter an awful lot because the execution makes it worse (and impossible to care). The dialogue is unrelievedly wooden, the characterization non-existent, and the acting uniformly of high-school talent show caliber. Even the TF effects, though done by Stan Winston, are below par. The ghoul sprints around like an enraged version of the Wicked Blair Witch of the West, and when we do glimpse her, with her porcelain mask and hooded robe, she looks either like an airborne version of the “Scream” stalker or–even better–a tattered lookalike for the emperor from “Return of the Jedi.”

To give the movie its due, “Darkness Falls” will succeed in eliciting easy gasps from less jaded viewers–those likely to jump out of their seats when a cat bolts onto a car hood or a face suddenly appears through a windowpane, which are only two of the obvious ploys used in the flick–but such bits are little more than the cinematic equivalent of “Boo!” endlessly repeated. Most of the audience are more likely to yawn or doze than feel any pleasurable fright. According to the press notes, “Darkness Falls” originally ran 85 minutes. Now it’s been whittled down to 75. The editors are going in the right direction, and should be encouraged to continue their salutary work. Perhaps by the time they reach the point where the feature is no longer than the short film “Tooth Fairy” by co-scripter Joe Harris (which served as the inspiration–loosely conceived–for the current effort), we can allow them to cease. At present darkness may fall, but despite all the sound and fury on display, it’s dullness that rules.

Incidentally, this is the second horror movie in recent months to be based on the idea of childhood “night terrors.” The first was the unlamented “They,” which was on roughly the same level of accomplishment as “Darkness Falls.” Perhaps a new medical diagnosis, one truly grounded in reality, will soon be in the mouths of the clueless psychologists who inevitably pop up in such pictures: a phobia denoting the fear of really lousy would-be thrillers.