CANNES, FRANCE -- The second week of the Cannes Film Festival got off to a bracing start with screenings of David Cronenberg's A History of Violence and Danish director Lars von Trier's Mandalay, his second film in his USA trilogy. The films are among the strongest so far and both have churned up a lot of discussion.

At first glance, A History of Violence looks like the most mainstream thing the Canadian director has done: A family man protects his family against evil interlopers. It's the disturbing details that make the story get under your skin. In an idyllic Midwest town, Tom Stall (Viggo Mortensen) is the boyish nice guy who runs the local diner, and his wife (Maria Bello) is a lawyer. They have a teenaged son and a little girl. One day, there's an ugly incident when a couple of thugs come into the diner, and Tom emerges as a vigilante hero. Tom's story gets national press and some unexpected baggage: Two mobsters arrive from Philadelphia and insist Tom's not who he says he is. When they won't leave, there's more trouble and finally, to protect his family, Tom has to take a trip to Philadelphia to visit a crime kingpin. Cronenberg has asked reporters not to reveal much more, for fear of spoiling the movie.

Stories about quiet men who unleash their gift for violence to save their families aren't exactly rare in American movies. After reading the script, which was inspired by a graphic novel, actor Mortensen wondered why Cronenberg took the project on.

"I thought it was interesting, but most directors would make an exploitation movie out of it and it might have been interesting to look at, but not very thought-provoking. Obviously, he makes thought-provoking movies, so I wondered why he wanted to do this one. I asked him immediately. He gave -- and continues to give -- interesting answers."

Cronenberg calls all the familiar trappings of the story the "transparent surface that obscures the complexity." Among the ways he says his film is distinguished from similar genre movies: "First, it's about the effects of violence on a family. Usually, the typical hero would be a loner, perhaps he drinks, that sort of thing. This is about what violence does to the people around him."

Unlike most action films, the film shows what wounds look like. The fights aren't full of kung fu movie choreography or Tarantino splatter. The fighting is blunt, fast and vicious. (For research, Cronenberg used hand-to-hand combat manuals on killing.) We see what happens when a bullet hits someone. There was, he says, "a lot of talk" with the studio about some of the shots of wounds but he refused to budge: "If I left those shots out, do you think the film would be better?" he asks. "In fact, those shots are very quick. The idea is to say: This violence is real. It has an impact on the human body that is not very pleasant and has horrific consequences."

Perhaps even more intense than the killing is the sex, particularly in a violent, though consensual, scene between husband and wife. The scene, set on a stairway, took two days and was actually shot on two separate sets (one on the stairs, one looking down from the storey above).

"It was terrible," said Bello. "I just remember walking around in a daze. This was so brutal and more psychological and emotional and spiritual than it was physical. And we got very brutal. I had bruises all over my body and scabs on my back. Viggo had a bite on the inside of his mouth. At the same time, it also was extremely technical, so we'd stop to look at the monitor: You know, move-your-leg-here kind of thing."

A woman reporter actually asked her what it was like kissing Mortensen, and Bello answered: "In my case, painful."

Cronenberg was inspired by Bello's injuries to add a scene showing the scabs on her character's naked back.

"Sex and violence," he said, "go very well together, like bacon and eggs. You can see in the movie the repulsion that Maria's character feels toward the violent element in her husband's character. The scene on the stairs is intended to show there's also an attraction. Sex is very complicated. That's one of the things that is nice about it. It reveals many things that are surprising about yourself."