'The Boy Next Door' is a plodder of a thriller

For a hot sociopath, Noah Sandberg sure is tedious.

Barely legal Noah (Ryan Guzman of the "Step Up" dance-movie franchise) seems like an all-American, model-handsome nice guy when he moves in with his elderly uncle to help him recover from a transplant. He and his triceps befriend next-door neighbor Claire Peterson (Jennifer Lopez), who teaches "the classics" at the local high school, and her allergy-prone, picked-on son Kevin (Ian Nelson).

Claire is separated from her cheatin' husband (a practically sleepwalking John Corbett), who is bent on reconciling. But when father and son go camping for the weekend, the molten stares that Claire and Noah have been exchanging from their upstairs windows, fueled by an apparent mutual love of Homer, turn into the inevitable night of slo-mo choreographed grappling.

When she tells him it was a one-time-thang big mistake, young Jekyll begins to show his Hyde side, quickly escalating threats to harm Claire's career and family — and also auditing her class. Yet for all his sudden fits of violent temper and plastering her classroom with compromising photos, Guzman can't muster up a truly scary persona.

Kristen Chenoweth offers camp relief as Claire's BFF, the school's vice principal. But with the exception of that one steamy sexual encounter between two super-toned bods (very nice navel, J. Lo) and a nail-biter involving an out-of-control car on a curvy cliff road, "The Boy Next Door" is a string of situations in which the actors' Job One is keeping straight faces while uttering lines like, "A woman like you should be cherished." Until the end, with a fiery climax so ridiculous it prompted bursts of laughter from a preview audience.

Director Rob Cohen ("The Fast and the Furious") knows his way around action scenes, but can do only so much with the clunky script by first-timer Barbara Curry, a former assistant U.S. attorney whose MFA in screenwriting from UCLA doesn't appear to have given her much practice in dialogue.