IL RAGAZZO DELLA PORTA ACCANTO: ATTRAZIONE FATALE PER JENNIFER LOPEZ CHE FINISCE NEL LETTO DEL BEL RAGAZZO DELLA PORTA ACCANTO MA... NON SARANNO ESATTAMENTE ROSE E FIORI

JENNIFER LOPEZ HAS A FLING WITH THE WRONG PSYCHO IN THIS SILLY BUT COMPETENTLY MADE THRILLER.

Director Rob Cohen is an old hand at straightforward genre product, with a career that stretches from “Miami Vice” to “The Fast and the Furious,” and he helms the Jennifer Lopez starrer “The Boy Next Door” with the passionless precision of a filmmaker who knows the territory. That might not sound like a fatal flaw, but frankly, a hack might almost have been preferable here, injecting this silly, somnambulant thriller script about a schoolteacher who falls for a psychotic teenager with some sort of panache, distinction or perversion, or even some kind of memorable incompetence to liven up its assembly-line paces. January releases don’t get much more January than this, but given its reported $4 million budget, “The Boy Next Door” shouldn’t have too much trouble finding its way into the black.

Lopez stars as

Claire Peterson, a San Fernando Valley high-school teacher who has recently separated from her philandering husband Garrett (John Corbett). Though you wouldn’t know it from the flawless makeup and runway-ready wardrobe she wears while grading papers in her mini-mansion, Claire is feeling lost and lonely, and struggling to raise her nebbishy teenage son, Kevin (Ian Nelson), alone.

Help arrives in the form of hulking, ingratiating Noah (Ryan Guzman), whose bulging biceps appear onscreen several seconds before his face does. A 19-year-old San Bernardino transplant, Noah has just moved in next door to help care for his ailing uncle, and in spite of some vague references to an “accident” in his past, he manages to effortlessly wedge himself into Claire’s life over the course of about five minutes, fixing her car and garage door, showing up for dinner, and helping Kevin gain the confidence to talk to the neighborhood hottie. (Needless to

say, in addition to his expertise with auto repair, he’s also a skilled computer hacker and a kickboxer who can quote long passages of “The Iliad” from memory.)

When Kevin leaves for a weekend camping trip, the inevitable transpires, and Claire gets hot and heavy with the titular next-door boy. No sooner has she attempted the next morning’s walk of shame, however, than Noah turns on a dime into an obsessive stalker, appearing unannounced at her home and somehow getting a seat in her high-school literature class. The film’s initial formulaic competence gives way to outright preposterousness rather quickly, hinging on idiot-plot character motivations, “It was only a cat!” jump scares and computer files that may as well be labeled “Evil Schemes, 2012-2014.”

Perhaps most fatally, the screenplay (by first-timer Barbara Curry) never bothers to question the nature of Noah’s madness, leaving the underprepared “Step Up” veteran Guzman adrift in a pivotal

role. It doesn’t help that his attempts at smirking, unhinged malevolence are more Ace Ventura than Norman Bates, nor that he’s clearly a decade older than some of the actors playing his schoolmates, but he has precious little to go on.

For its budget, “The Boy Next Door” looks decently polished, and Cohen stages one runaway car chase scene with the kind of kineticism that suggests he’s aching for another go at the “Fast” franchise.