Alex Gibney was a producer of last year's No End in Sight, and with Taxi to the Dark Side, his documentary about torture perpetrated by U.S. forces in Afghanistan and beyond, offers that film a steadfast psychic twin. Both titles seem unfortunately dramatic -- or too generically dramatic -- given the truly, uniquely dire subject matter, but the starkness they suggest gives only the barest lie to that which the filmmakers describe in full.

Gibney, best known for his last chronicle of another Great American Meltdown, Enron: The Smartest Guys in the Room, begins his wide-ranging takedown of the Bush administration's military policies on torture and interrogation with the story of Dilawar, an Afghan taxi driver caught up in an all-too-common intelligence boondoggle. The son of a peanut farmer, Dilawar was apprehended on Dec. 1, 2002 and taken to Bagram prison, a former Soviet facility being used by the Americans to incarcerate and interrogate suspected terrorists and insurgents. Initially these prisoners are referred to, by Spc. Damien Corsetti, who was stationed at Bagram prison at the time, as Persons Under Control (PUC) -- an acronym that is later described by a higher-ranking official as Persons Under Custody. It's a telling distinction and, as Gibney goes on to argue, one of several crucial ambiguities that the Bush administration relies on; soldiers are given enough leeway and enough pressure to produce "results" to make their own interpretations of the rules, to make hay while the sun don't shine.

Threading in and out of Dilawar's story (he spent five days at Bagram prison before being beaten to death), Gibney uses the testimony of several of the soldiers on duty the night he died (all of whom were later charged in some capacity with the death and served sentences at home) as a springboard into the larger quagmire of interrogation policy, or lack thereof. Mapping the timeline from 9/11 through the invasion of Afghanistan, the opening of Guantanamo Bay, Bagram prison and then Abu Ghraib, a forceful argument is made for the utter disintegration of ethical accountability (not to mention adherence to the Geneva Convention) at the highest levels of American government.

Gibney follows that disintegration down the chain of command and across the world, where men like Corsetti, Pfc. Willie Brand and Spc. Tony Lagouranis slowly lose their moral bearings, treating the prisoners they are supposed to be guarding and questioning like vermin, interpreting the constant stream of memos about what is and isn't considered acceptable interrogation technique as they and their increasingly frazzled psyches see fit. Dilawar was the second prisoner to die in Bagram in the space of a week, and the men responsible for his death knew that meant trouble. Even so, the reaction is chillingly oblique. "They are very frail people," one soldier says. "I was surprised it took that long for one to die in our custody."

Although perhaps not as tightly and concisely organized an indictment as No End in Sight, Taxi to the Dark Side's impact is ultimately not affected by its sprawl; the ripple-effect structure Gibney attempts matches the outward spiral of events that have lead us to the shameful spot we are in now, though the diluted focus can at times prove hard to follow. Photographing the soldiers in half-shadow, their trauma and even their implacability are striking contrasts to the horrifying imagery of torture, Dilawar's pulverized corpse, and photos and footage from Abu Ghraib that have not been widely seen. Gibney gained access to Moazzam Begg, the British National who was detained for two years at Bagram and Guantanamo, most of the players involved with Dilawar's death (with the notable exception of Carolyn Wood, who took the practices first used at Bagram on to Abu Ghraib) and advisor in Bush's Office of Legal Counsel John Yoo, author of the infamous "Torture Memo,"who coolly defends the merits of such a mandate in the face of such an enemy.

The details amass in a sickening pile, the final blow coming via the revelation that Dilawar's arrest was not just absurd but obscene; 94 percent of the prisoners in Bagram are arrested by Afghan militiamen, who work for cash bribes and petty vendettas. It's a circle of death and treachery that spans the globe and depends on the darkest stretches of human nature to be complete; Gibney's tracking of this country's part in that circle -- our recent moral hairpin curve -- shows how quickly and how completely we can forfeit what makes us good, as people and as a people.