Sam Rockwell, Jacob Kogan, and Vera Farmiga in Joshua Photo by Jojo Whilden

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Audiences have faced down a whole rogue's gallery of cinematic villains, from pale-faced bloodsuckers and chainsaw-wielding masked men, to psychotic hotel proprietors and cannibal doctors. So how scary could a nine-year-old boy be, especially one who just wants to be loved? Already a cult fave among the crowds at this year's Sundance film fest, Joshua follows in the tradition of bad-seed classics like Rosemary's Baby, Village of the Damned, and It's Alive. Just don't call it a horror flick, since there isn't any gore, nor much else in common with recent torture-fests like Hostel: Part II or The Hills Have Eyes remakes.

"I think it's a psychological thriller with a little bit of comedy, if you're gonna label it," insists Sam Rockwell, who stars as Brad Cairn, an upwardly mobile Manhattanite and expectant father with his wife Abby (Vera Farmiga). Baby Lily isn't the couple's first child, but while they're very proud of their piano prodigy son who gives the film its name, it's easy for them to focus all their doting energies on the newborn. This, as you might guess, doesn't sit well with the super-intelligent Joshua (Jacob Kogan), whose growing unhappiness with his folks' seeming neglect might be the trigger for some sociopathic behavior. Will the baby be safe if Joshua is half as disturbed as his cold deadpan suggests? It's hard enough worrying about Joshua's uncle, grandmother, and the poor family dog, but how are his parents supposed to love a child they're scared to tuck in at night?

Rockwell elaborates on the uneasy father-son tension: "I like him in the beginning, but there's something fuzzy in the relationship. We're not quite jibing, me and the kid. He's my son, and I'm trying to care for him and be the best dad I can, but we're all sort of suffering from postpartum disorder, in a way. And then it gets accelerated by this demon child."

Cowriter-director George Ratliff — probably best known for his similarly frightening, religious haunted-house documentary Hell House — wanted to explore these specific familial dynamics for his narrative debut.

"What was exciting to me was that it played with a primal fear that everyone who thinks about having kids has," Ratliff says. "I came across it when my brother had his first son. I was riding in a car with him, and I said, 'This kid could be a doctor or a lawyer.' He was just driving, and very solemnly said, 'He could be a serial killer.' Oh my god, that's true. He could be!"