"A History of Violence" is a Trojan horse: Like the majestic wooden structure that stood before the walls of Troy -- secretly carrying armed Greek soldiers in its cavernous belly -- David Cronenberg's film has its own hidden and powerful purpose. Seemingly a mainstream shoot-'em-up flick, in which the soft-spoken Tom Stall (Viggo Mortensen) defends his family against a horde of hoodlums, the movie's really about our Pavlovian conditioning to violence.

Life seems permanently asleep in the Midwestern hamlet of Millbrook, Ind., population 3,246. That is, until two men barge into Stall's diner one night, demanding coffee. When Tom tells them it's closing time, he finds himself staring at a drawn gun.

Tom emerges the victor and within 24 hours he's a media hero, but then the questions begin: How did this unassuming diner owner dispatch the gunmen so effortlessly? ("I just got lucky," Tom insists.) Why do more gangsters, led by scar-faced Carl Fogarty (Ed Harris), keep coming for him? Why do they think that his real name is Joey and that they have unfinished business? Tom's wife, Edie (Maria Bello), starts to wonder to whom she's married.

Ultimately, though, Cronenberg's drama isn't about western-style heroism or the importance of protecting yourself against a hostile world. It's about why we're cheering when he plugs them dead.

-- Desson Thomson