Actor Jeremy Renner was having a kind of off-camera, post-traumatic stress moment. For nearly half an hour, the 38-year-old performer had been chatting, eloquently and amiably, about acting, the Middle East and his lead role as a U.S. Army bomb squad technician on the streets of Baghdad in Kathryn Bigelow's calculatedly nerve-racking new film, 'The Hurt Locker,' which opens Friday here and in New York. In one crucial scene, Renner's character, an outwardly cool and pragmatic but inwardly roiling staff sergeant named William James, must confront an Iraqi suicide bomber who wants out of his lethal mission. 'That was one of the toughest scenes for me,' Renner said, pausing between sips of coffee and drags on a cigarette, ' 'cause that broke my heart.' Abruptly Renner's voice froze, his eyes watered and a silence of several seconds ensued. He appeared to be 10,000 miles away from the fog-enshrouded garden of the Chateau Marmont. 'I'm sorry, I don't know why it affects me so much, even now,' the actor murmured, adding that he had broken down crying at the end of filming the scene. So had virtually the entire Jordan-based film crew, according to others who were on the set that day. By several accounts, making 'The Hurt Locker' was an obstacle course, exhilarating and enriching but lined with logistical and emotional booby traps. Rather than a 'war movie' per se, the film is a superficially straightforward but exceptionally subtle story about what makes the hard-wired human animal tick. Although the film is fictional, it's based on extensive reportage by screenwriter Mark Boal, a journalist who was embedded with the U.S. military in Iraq. The movie's visceral challenges, from the 125-degree heat (hotter if you're encased in a protective bomb-disposal suit) to the cultural exoticism of the locale, were abundantly real, Renner said. That verisimilitude, along with the movie's calibrated adrenaline rushes, may help 'The Hurt Locker' command a larger audience than most Iraq War-themed movies have done. 'I'd never been in the Middle East, and I learned a lot being there, and it was very physically demanding and spiritually straining,' Renner said. 'I was Google-mapping my self-respect and my dignity. It really took it out of us.' Yet it's in such extreme situations as the film depicts, of loss and fear, desperation and danger, that we may learn who we really are, Renner said. 'If you're stuck in a forest and you have no compass, and you need to eat and whatever, we'd be having a very different conversation. How do you succeed in life when you come up against an obstacle, a wall? Do you sit and suck your thumb and cry? Do you climb over it? Do you go around it? Do you try to break it down? Very telling of an individual.' Judging by his casual exterior, in a white T-shirt and jeans, Renner looks to be pretty much the individual that he is: an easygoing guy from Modesto, Calif., who loves hiking and being outdoors (he rehabs houses on the side). But raw, unsettling emotions are an occupational hazard of certain professions, acting among them. Especially, perhaps, if you gravitate toward tightly wound, somewhat deceptively placid characters whose Everyman features mask turbulent inner lives. Renner has portrayed a few of these intricately layered types: Doyle, the intrepid soldier who disobeys orders to save a group of survivors in the apocalyptic horror film '28 Weeks Later'; Gus, a grief-stricken firefighter fleeing a haunting tragedy in '12 and Holding' and Detective Jason Walsh on the ABC cop drama 'The Unusuals,' who tells a colleague, 'I think we are our secrets.' Those roles followed his career-making turn in 'Dahmer,' as the real-life serial killer who for years slipped barely noticed through polite society. His 'Hurt Locker' character is a Southern good ol' boy whose combination of sang-froid expertise and borderline recklessness arouses both admiration and alarm from others in his elite Explosive Ordnance Disposal squad. Boal said that Renner 'has a very sort of hail-fellow-well-met kind of demeanor. But he's actually quite, quite serious about what he does. He was invested in the reality of it, everything from the way he disarms the bomb and holds the pliers to being psychologically authentic too.' The art of partially concealing oneself behind a layer of armature is an essential acting skill. Renner began acquiring it as a child, struggling with his parents' divorce while maintaining good grades and an upbeat facade. 'I was happy, but only happy on the outside,' he said. 'So that's when 19 years of emotional repression came to the stage, and it became a playground for me to have all these feelings.' Today, he's close to all members of his reconfigured clan. Like Sgt. James, he's sophisticated enough that he can afford to bend the rules now and then. 'It's just about completing the task and, hopefully, enjoying yourself along the way,' Renner said. 'That is the best thing, to enjoy that journey, to completing whatever task that might be.' 