Grade: F

It wouldn’t be Halloween without a cheap, chintzy horror movie, so here it is. “The Haunting of Molly Hartley” can best be thought of as a pint-sized high school version of “Rosemary’s Baby,” with all the teen angst that description suggests. It’s not a pretty issue.

Molly (Haley Bennett) is a kid who’s understandably disturbed by the fact that her mother (Marin Hinkle) tried to stab her to death without the usual provocations. She moves from Boston to the town outside which mom is now confined in a nice (and apparently porous, since she frequently escapes) psychiatric establishment, where she enters one of those old-fashioned prep schools beloved of screenwriters. From there on we find a pretty standard group of characters. Over-protective dad (Jake Weber). Stud who takes a shine to her (Chace Crawford). Bitchy blonde who thinks he belongs to her (AnnaLynne McCord). Sarcastic outsider who becomes best pal (Shannon Marie Woodward). Bible-thumping geek (Shanna Collins). Too-cool English instructor (Josh Stewart). And, of course, the suspiciously solicitous guidance counselor (Nina Siemaszko) who just happens to be new at the school, too.

Everything is directed toward Haley’s imminent eighteenth birthday, when—as a prologue involving another unfortunate girl (Jessica Lowndes), her boyfriend (Randy Wayne) and her father (Jamie McShane) indicates—something horrible is going to happen. But you don’t have to wait for the celebration of her maturation to experience terrible things, because the script (by neophytes John Travis and Rebecca Sonnenshine) is a succession of them—and I’m not talking about the klutzy shock effects (dogs and birds jumping into frame accompanied by loud music cues courtesy of James T. Sale, abrupt ghostly apparitions, and so on) but the idiotic plot twists. Nobody could have brought this tripe to life, but director Mickey Liddell certainly isn’t the fellow to do it, nor cinematographer Sharone Meir.

The acting’s awful down the line (Ron Canada comes off best as the school principal, because he has only a single brief scene near the beginning before disappearing quickly while the getting is good), with Bennett working up a storm to no effect, Weber and Collins especially embarrassing themselves, and Crawford (who dealt with a similar eighteen-is-approaching scenario in Renny Harlin’s 2006 bomb “The Covenant,” which at least had higher production values than this bargain-basement effort) trying desperately but unsuccessful to come across as really smooth.

Even for the holiday, this stinker is a maladroit trick rather than any kind of Halloween treat.