'We Need To Talk About Kevin' Trailer: Ezra Miller Freaks Tilda Swinton & John C. Reilly (VIDEO)

What happens when your sweet little boy... isn't?

That's the question presented by festival favorite indie flick, "We Need To Talk About Kevin," which stars Ezra Miller as a dark, psychotic young man and Tilda Swinton as his beleaguered mother. Her husband, played by John C. Reilly, seems either optimistic or delusional about their son's darkness, complicating even further Swinton's efforts to understand and communicate with Kevin.

The name makes more sense in the context of the film's origin; the Lynne Ramsay-directed flick is based on a 2003 book of the same name by Lionel Shriver, who used the unusual narrative form of a series of letters from wife to husband tell the story.

The picture won the big prize at the London Film Festival, and is serving as a good launching pad for Miller, who will next star in another book adaptation, "The Perks of Being A Wallflower."

"We Need To Talk About Kevin" hits theaters on December 9th.

WATCH: