Grade: C-

This supernatural thriller from Scott Derrickson (“The Exorcism of Emily Rose”) has been getting some reasonably respectable reviews since it screened at Austin’s SXSW festival last spring, which is surprising since it’s no better than most of the genre stuff that studios regularly shovel into theatres nowadays, and in some ways worse. It does earn points for avoiding the ultra-tired “found footage” style even while the story is based on newly-discovered film. And it boasts a cast that features a few recognizable names rather than the usual cavalcade of unknowns, though that’s not a particular strength when the script is weak, as it is here, or the scares depends on the hoariest of devices. It’s in these respects that “Sinister” fails to deliver the goods.

Ethan Hawke stars as Ellison Oswald, a true-crime writer on a downward spiral who moves his family—wife Tracy (Juliet Rylance), son Trevor (Michael Hall D’Addario) and daughter Stephanie (Victoria Leigh)—into a remote house where four members of a family were hanged on a tree in the backyard. (The fifth, their young daughter, simply disappeared.) His object is to investigate the unsolved murders, much to the disgust of the local sheriff (Fred Dalton Thompson), who doesn’t respect Oswald’s habit of bad-mouthing cops. The whole business is complicated by the fact that Ellison hasn’t bothered to come clean with his wife about the house’s past.

The plot kicks in when Oswald finds a box of old 8mm films in the attic. One canister contains footage of the actual hanging that happened at the house, and the other reels document several equally horrendous killings of families. With the help of an obliging deputy (James Ransone), who’s hoping for a mention in the acknowledgements of the book Ellison’s writing, he discovers that in each of the cases—which go back to the sixties—a child went missing after each slaughter.

But there’s more. With the help of the inevitable academic who specializes in occultism (Vincent D’Onofrio), Oswald learns that a symbol found at each crime scene refers to an ancient pagan deity known to specialists as the “child eater,” who approaches his human victims through images of himself. And lo and behold, on the edges of the footage Ellison scrutinizes, he spies a black-garbed, demonic figure. Surely it’s no accident that little Trevor is suffering from awful night terrors, while Stephanie has a habit of drawing pictures on her bedroom wall.

This isn’t a bad premise, and if the script Derrickson and C. Robert Cargill had done something interesting with it, the movie might have developed some resonance. (If Oswald had faced some sort of Faustian bargain to hand over his kids, for instance, the narrative might have gone somewhere.) But instead it just ambles slowly along. Most of the time it consists of the camera following Hawke wandering around the house, whiskey glass at the ready, as the place emits creaks, groans and other spooky sounds, all predictably juiced up by the grinding and whooping of Christopher Young’s electronically-dominated score. Hawke conveys the mental deterioration of the character adequately enough over the course of events, but since he’s an actor who manages to look haunted even in romantic comedy, that’s hardly a stretch, and as a performance his can’t hold a candle to Jack Nicholson’s as another writer-on-the-way-down in “The Shining.”

But worse than the repetitiveness is the increasing silliness as the tale rambles on. When D’Onofrio gives the god’s name as Bughuul, for example, you’re likely to giggle—certainly that’s the worst name for such an entity since we were told that the “Exorcist” demon was called Pazuzu. When wraithlike children begin appearing around the house like refugees from a Japanese ghost flick, you’re more likely to shrug than jump in your seat. And worst of all, when Ransone drops a clue that’s the key to the whole business and the supposedly clever Oswald fails to pick up on it although even the most bored viewer will do so, you realize that the writers have little respect for their audience. (That clue also telegraphs the ending, so that what’s supposed to come as a shock proves a pretty damp squib, which Derrickson makes even worse by adding a final freeze-frame that’s the epitome of cliché.)

Chris Norr’s cinematography is appropriately atmospheric, and the overall production is a tad above what one ordinarily encounters in this kind of fare. But though youngsters D’Addario and Leigh are attractive kids, only Ransone scores among the adults in the supporting cast, his deadpan approach adding some welcome humor to an overall gloomy tale. By contrast Rylance is shrill, and Thompson looks grumpier than when he dropped out of the 2008 presidential primaries. As for D’Onofrio, this is one of the rare instances when one can actually say that he’s phoning it in.

“Sinister” is actually less scary than the first season of “American Horror Story,” which used many of the same devices to better effect. As to why some reviewers are giving it high marks, maybe they’re writing under the influence of Bughuul.