Despite the ambiguous "mission" being "accomplished," more than 4000 American troops have lost their lives in Iraq since that famous banner adorned the USS Abraham Lincoln waaaaaay back in the spring of 2003. And when the time comes to relay the devastating news to the surviving family, that honor falls to what is known as a casualty notification officer, who shows up at the home of someone they don't know to inform this stranger that their loved one has met a violent end half a world away. The CNOs are an unseen, unsung reality of war, one that stands front and center in Oren Moverman's "The Messenger," an insightful and resonant character study about two CNOs and the survivors they encounter as they carry out their unimaginable task.

Ben Foster stars as Staff Sargeant Will Montgomery, newly returned from the Middle East a decorated war hero with the scars to prove it. For the last few months of his enlistment - and much to his obvious distress - Will is assigned the job of "bereavement notification" and teamed with Desert Storm vet Captain Tony Stone (Woody Harrelson, in his Golden Globe-nominated role). Cinematic law dictates that this pair be of differing temperaments, and they are: Will is quietly edgy, trying to adjust to life outside a combat zone; whereas the older Tony is brash, chatty, and surprisingly needy. Tony instructs Will as to the rules of their mission, which include sticking to the unemotional script and refraining from contact with the next of kin, but you know what they say about rules.

I don't mean to make "The Messenger" sound predictable; as a matter of fact, the reactions of the families, from denial to gratitude to crippling despair, were shot on the fly and largely improvised, both adding to the tense immediacy in the wrenchingly long seconds after the doorbell rings and allowing for equally visceral responses from Foster and Harrelson. The most recognizable faces among the survivors are Steve Buscemi, popping up in a small but powerful turn as a father whose grief takes the form of spitting rage, as well as British actress Samantha Morton, playing a recently notified widow with whom the lonely Will forges a connection. The absurdly gifted Morton uses her pleading eyes and weary carriage to convey Olivia's struggle with survivor's guilt as she mourns a memory rather than a man.

In the 10 years since his big-screen debut in Barry Levinson's "Liberty Heights," the versatile Foster has been discreetly cementing his status, alongside the Goslings and the Ledgers, as one of the best of his generation. Foster owned "3:10 to Yuma" with his gonzo portrayal of a psychotic gunslinger, and his subtly defensive vulnerability, a la Nicolas Cage, serves him well in a role that requires him to be an outsider in his own world. When he's not holding his own with the masterful Harrelson as Will and Tony bicker and bond over what it means to be a soldier, Foster enjoys more serene moments with Morton in which their characters tentatively navigate the boundaries of their attraction. There's one erotic, wordless interlude between Will and Olivia that some might think prolonged, but anyone who's ever fallen for someone inconvenient will recognize that scene's sad truth.

"The Messenger" is Moverman's directorial debut; he previously penned the surreal Dylan flick "I'm Not There" as well as 1999's superb "Jesus' Son" (which also featured Morton). The Israeli-born Moverman co-wrote "The Messenger" with Alessandro Camon, basing the candidly observed script on his experiences during mandatory service with the Israeli Army. With the sole exception of the contrived drama found in the party-crashing scene, the results are challenging and refreshingly nonjudgmental against both soldiers and civilians, eternally unable to bridge the schism between those who have endured hell and those who can't even begin to imagine it.