Terror is existential in this highly intelligent, somewhat sadistic, totally fascinating movie. Identified in the manner of a French "new novel" only as She, the teenaged suicidiste (Luisa Williams) is introduced on a cross-country bus en route to her fatal rendezvous. "Everybody dies," she chants in an accent-free whisper. "My death will be for you." It's the nature of the You that Loktev leaves the viewer to ponder for the duration of this structural thriller.

As its title suggests, Day Night Day Night has two halves. The first is devoted to the preparation. She gets off the bus and contacts her handlers, is taken for a quick ramen dinner, and dropped at a nondescript New Jersey motel. Awaiting further instructions, She bathes, shaves her armpits, clips her toenails, and washes her clothes—anxiety mounting despite, or perhaps because of, these banal, yet final, activities. Before her hooded handlers arrive, She blindfolds and handcuffs herself. They give her instructions and invite her to ask questions (which they ignore). Barely treated as human, She touchingly invites her masked comrades to share the pizza that's been ordered. She doesn't want to eat alone.

The Russian-born, 30-something Loktev has an extremely dry sense of humor. The three ski-masked palookas suggest that She might want to record a video for her parents. "My parents are dead," the girl timidly offers. No matter, She's dressed up in vaguely military garb and posed, holding a carbine, before a generic militant backdrop. As a costume for the mission, She models a bunch of Kmart outfits. (Finally, the handlers nix the pink Baby Girl zippered sweatshirt in favor of a striped sweater.) She's given an identity to memorize and interminably drilled. Process is all: This cell has no obvious politics, no apparent religion, no overt nationality.

The mission is all about directing a performance—as is the movie. Williams, a neophyte actress who Loktev says she chose from 650 candidates (perhaps, because as the press notes maintain, the actress developed a tween crush on Anthony Perkins's Norman Bates), has Mediterranean coloring, a tentative little voice, and a not-quite crucifix around her neck. Her character is obedient, fastidious, and dutiful; her sharp features are squeezed together, large eyes sunk deep within the heart-shaped, bony face that frequently fills the screen. It's a great turn—a virtual solo. (Not since Bresson's Trial of Joan of Arc or the Dardennes' Rosetta has an actor been so closely and continuously observed.) Williams's intense focus may mirror that of her director; Loktev's first feature Moment of Impact was a disturbingly intrusive documentary on the daily life of her severely disabled father.

Day Night Day Night's second half begins with She's emergence from the Port Authority outfitted with a lethal backpack ("It's about 50 pounds, but most of the weight is in the nails," She's been told) into the sensory bombardment of midday Eighth Avenue. Walking through the crowd, She resembles the Professor in Joseph Conrad's The Secret Agent, although Loktev's model is more likely Hitchcock's Sabotage—the grandfather of all suicide-bomber flicks, including Hany Abu-Assad's more politically "responsible" Paradise Now.

The camera runs free, and over-stimulation reigns: She seems dazed, asking the way to Times Square and proceeding down the Deuce with a big mustard-slathered pretzel in each hand. Someone slams into her, tourists ask her to take their pictures, police sirens blare, unwelcome suitors appear. She ducks into in a huge candy emporium for a jelly apple. (Food is an issue throughout.) Free-floating anxiety gives way to fear and trembling, being and nothingness, curiosity and impatience. A public toilet must be negotiated—as well as a pay phone.

So what's the game plan? Where's the moment of impact? At key moments, the crowd is reduced to extreme close-ups of individual gestures, the sound cutting in and out like waves pounding the beach. Time stands still; the wait is interminable. However low-budget and minimalist, this digitally shot, quasi-guerrilla production is a new-style disaster flick—as experiential in its way as the ritual ordeal provided by United 93.

Were it not for it's durational aspect, Loktev's concept might also have been realized as a performance piece or a gallery installation. Unlike Paradise Now, Day Night Day Night has no interest in mapping the prime mental terra incognita of contemporary politics: The movie has nothing to do with the psychology of the suicide bomber and everything to do with the psychology of the spectator.