What was it like getting into a serial killer’s head? We asked Kevin Costner on Tuesday evening at a Tribeca Grand screening of his new thriller, Mr. Brooks. “Well, it was surprisingly easy,” he replied. After further reflection, he added, “I don’t feel really good about saying that.”

Wearing jeans and sporting a graying goatee, the craggily handsome Costner looked relaxed on the surface, not unlike his character Mr. Brooks, an upstanding pillar of the Portland, Oreg., business community. But just like the character, Costner had more going on than met the eye. Mr. Brooks is “addicted” to killing people, and the little voice inside his head – actually, a whole person played by William Hurt – won’t let him stop. Costner's calm demeanor, meanwhile, belied his worries about the commercial fate of his latest project. “You make a movie like this, and you’re really not sure anybody’s going to show up,” he said while introducing the film. “The fact that you have really makes me think we should have charged tonight. This might be our sellout.” —Bennett Marcus