Weak movie comedies often boil down to a simple counting of laughs. For meek horror films, you track the "gotcha" count.

Those are the cheap scares the filmmakers throw your way — a dog lunging against a fence from out of nowhere, an ill-timed game of "Guess who?" by a sneaky boyfriend, birds bursting out of a bush as a character walks by, ominous music moaning from the cellos.

"The Haunting of Molly Hartley" manages about a dozen of these, each cheaper than the one before. But it's still more novel than your average "Saw" installment, a chiller of modest ambition if unskilled execution.

Haley Bennett plays Molly, the new kid in a fancy prep school, a girl running from her past, disturbed by her dreams, one who hides a scar under her uniform. Shanna Collins is Alexis, the first girl to be friendly. But she's a religious fundamentalist — not cool to the other kids. And she's kind of creepy.

Joseph (Chace Crawford of "Gossip Girl"), the pretty rich boy, is interested. And Leah, played by Shannon Marie Woodward (of "The Riches") as if she's watched "Juno" a few too many times, is the sexy Goth chick who tries to take the new girl under her wing.

Molly keeps having panic attacks, nosebleeds and other episodes as her teacher tries to impart the lessons of "Paradise Lost." She's scaring Dad to death, but the doctors and her counselor think they have a handle on it. That doesn't account for the voices, the nightmares about what happened to Molly that put her in this state.

Something's coming. It has to do with her 18th birthday. And it won't be pleasant.

Mickey Liddell, a veteran TV producer ("Everwood" had his hand in it) directed this. He's better at the high school parties, classes and cliches and the gimmicky cheap scares than at building the dread Molly faces, the doom she doesn't want to see. The plot isn't much, but the subtexts — religion, belief, disbelief, prophecy and the like — are fascinating horror fodder, and the young cast is game.

Bennett is much better in this than she was playing a vapid, vampy and childish pop singer in "Music & Lyrics." She makes Molly's actions and reactions feel real and age-appropriate.

But "The Haunting of Molly Hartley" isn't the least bit haunting. It's just cheap. And no dogs leaping against fences or birds flocking out of nowhere through the film frame can add enough value to make it otherwise.