In “Zero Dark Thirty,” the masterly new movie directed by Kathryn Bigelow and written by Mark Boal, a C.I.A. field agent has an Al Qaeda operative in his grip. The agent, whose name is Dan (Jason Clarke), a tall, handsome guy with a bushy brown beard, subjects the prisoner to “enhanced interrogation”—a full complement of pain, naked humiliation, and waterboarding. “This is what defeat looks like,” Dan tells the operative, who is named Ammar (and is played with sympathy by the French actor Reda Kateb). These words are spoken at a C.I.A. “black site,” in Pakistan, in 2003. But most of the movie is about American defeat—the failure to capture or kill Osama bin Laden, as Al Qaeda pulls off attacks in Saudi Arabia, Britain, and Pakistan. “Zero Dark Thirty” chronicles a long trail of frustration, leading to fragmentary gains and, at last, to success, on the night of May 1, 2011: Operation Neptune’s Spear, a Navy SEALs siege of bin Laden’s hideout in Abbottabad, which is so perfectly executed that it almost defies normal skepticism about the way life works. The virtue of “Zero Dark Thirty,” however, is that it pays close attention to the way life does work; it combines ruthlessness and humanity in a manner that is paradoxical and disconcerting yet satisfying as art. Ammar may be working for Al Qaeda, but he’s also a human being, and he’s suffering. Yet, in attempting to show, in a mainstream movie, the reprehensibility of torture, and what was done in our name, the filmmakers seem to have conflated events, and in this they have generated a sore controversy: the chairs of two Senate committees have said that the information used to find bin Laden was not uncovered through waterboarding. Do such scenes hurt the movie? Not as art; they are expertly done, without flinching from the horror of the acts and without exploitation. But they damage the movie as an alleged authentic account. Bigelow and Boal—the team behind “The Hurt Locker”—want to claim the authority of fact and the freedom of fiction at the same time, and the contradiction mars an ambitious project.