A shadowy figure makes his way through a grey hallway, so close and grim that the very air seems thick. He passes other people, uniforms baggy, heads down, their shoulders slumped and feet shuffling. At last, he pauses, his back against a wall, and the camera moves in, slowly. His face, smudged and weary, comes into focus: It’s David Arquette.

This moment of recognition is startling, no doubt. But it's not long before you begin to forgive it, to slide into the overwhelming greyness with him. For Arquette gives a memorable performance as Hoffman, a young Jewish man working, miserably, as a member of Auschwitz's 12th Sonderkommando. That is, he's a member of the second to last of the "Special Squads" of Jewish prisoners assigned by Nazis to process their fellow Jews through extermination, instructing them as they undress and file into the gas chambers, then loading bodies into the furnaces. In exchange for their "services," the squads are allotted a precious few more months of life, at the end of which, they are exterminated.

Tim Blake Nelson's The Grey Zone, adapted from his own stage play, traces the series of horrifically inevitable dilemmas that confront these Sonderkommandos. Nelson based his narrative on two sources: Auschwitz: A Doctor's Eyewitness Account, memoirs by Miklos Nyiszli, a Hungarian Jewish doctor who assisted Mengele, and an essay by Primo Levi, in his collection, The Drowned and the Saved. Relentlessly bleak, the film focuses on various prisoners as they plot against their captors, knowing they are doomed to die in any case, but endeavoring to blow up one of the furnaces anyway.

Hoffman works with Schlermer (Daniel Benzali), Rosenthal (David Chandler) and Abramowics (Steve Buscemi), meeting in their relatively deluxe barracks (they have blankets, books, cigarettes, plates), eating their relatively fulfilling rations (meat, wine). On the other side of the camp, several women, including Dina (Mira Sorvino), Anja (Lisa Benavides) and Rosa (Natasha Lyonne), also plan, knowing that when they are discovered, as they must be, they will be tortured beyond what they can endure. They can't help but agonize over their fate, but they keep on.

Two more characters offer other perspectives on the nightmare all endure: the camp commandant Muhsfeldt (Harvey Keitel) and Dr. Nyiszli (Allan Corduner), conducting "experiments" on selected subjects (for instance, twins or particular children). Bizarrely charged with keeping the prisoners alive (preventing suicides, treating sickness) until they are gassed and burned, the doctor exists in a particular limbo; dressed in a suit and ensconced in an office, with desk and paper for record-keeping, he daily wonders at his capacity for horror.

When a girl (Kamelia Grigorova) unexpectedly survives the gas, some of the Sonderkommandos, Hoffman and Rosenthal among them, call on the doctor to resuscitate her. This leaves them with yet another impossible quandary, for in hiding her from the guards, they risk everything.

The film thus lays out, in the most complex ways, the choices (or lack thereof) facing the prisoners. Their work is not heroic, as they are, after all, betraying incoming Jews when they tell them to remove their topcoats and make sure their belongings are precisely labeled with coordinate numbers, so they might find them once they are done with the "cleansing" procedure. Some of the prisoners have heard something about what happens in the camps and resist, challenging the Sonderkommandos.

Cinematographer Russell Lee Fine's handheld camera presses you repeatedly too close to the characters' perpetual fatigue and resilience, their pains to survive when they cannot. The smoke puffs endlessly from the furnaces, ragged armchairs offer momentary rest for body-shovelers on the grass outside the barracks. The Grey Zone is endlessly dreadful, offering neither heroic imagery nor comic respite, familiar from other popular and honored Holocaust films (say, Schindler's List or Life Is Beautiful). The characters exhibit courage, imprudence, meanness, generosity and fear, in situations that most of us can't even imagine. For all that it offers visually (it uses no score, for which it is to be commended), The Grey Zone's most compelling point is that what you're watching -- what you're trying to comprehend -- is, in the end, impossible to represent.