The hit-and-run drama of "Over the GW" is as grueling and disorienting as its grim subject: a drug rehab program that engages in cult-like dehumanization in the guise of boot-camp tough love. Based on director Nick Gaglia's own ordeals at just such an organization in the 1990s, the film's account of cruelty and wretchedness rings true, but the rough-hewn filmmaking and confusing storytelling withhold too much from the already battered viewer.

"Over the GW," which opens today at the Pioneer Theater, begins with the humiliating admission process for a young Bronx addict, Tony (George Gallagher), to a rural rehab center. Strip searches and repeated five-point restraint introduce him to his new world of pain. Humiliation and degradation at the hands of obnoxious staff and peers are the hallmarks of the program's day-long group sessions, which take place in a desolate, fluorescent-strafed room resembling a school gym in hell.

Convincing, documentary-style interview clips with Tony's father ( Nicholas Serra) and grandmother ( Minnie Krakowsky) break up the scenes of abuse. Trusting and oldfashioned, the two comment on the events after the fact, offering the film's only (and scant) explanation of the rehab program's bewildering escalation. (The movie's title refers to the family's fateful trip across the George Washington Bridge to drop their son at the program.)

But Mr. Gaglia, not interested in the critical remove of a documentary, lets the cabin fever and shell shock of the program define every aspect of his film. Watching "Over the GW" is like being trapped in the nightmarish hidden-camera portion of a newsmagazine exposé, at the hands of an impatient editor. The handheld camera scurries about, recording without explaining, and keeping the big picture at bay.

On the one hand, this yields a wrenching depiction of Tony's loss of will and the tyrannical control exerted by his handlers. We're yanked through bunker-like corridors and sleeping quarters, from one tirade to another; the camera ventures outdoors mainly when someone tries and fails to escape. Brutal Marxist-style peer condemnations grind on and on, incited by a saturnine head psychologist ( Albert Insinnia) who might not even be a real doctor.

But the storytelling in "Over the GW" is often needlessly cryptic, and not always because the drama bravely resists coming up for air. When Tony is joined by his sister Sofia (Kether Donohue), ostensibly for moral support, it's not clear why or how she then gets sucked into the program permanently. The vagueness might be faithful to the shattered memories of a survivor, but the uninitiated need some firm ground to stand on, especially to understand pivotal moments in what becomes a two-year stay for Tony.

It's also hard to move beyond a basic, visceral sympathy for Tony and Sofia, because the 75-minute film finds little time to establish their pre-brainwashed identities. Mr. Gallagher and Ms. Donohue's youthful charisma does at least make the horrific evacuation of Tony and Sofia's self-awareness that much more tragic.

"Over the GW" ably observes all the Orwellian details of cult-style programming. The "doctors" force patients to refer to suspect relations as "druggie friends," whether or not they are involved in drugs, and the inmates' thoughts are so regulated that it is forbidden to read even the back of a cereal box. Perversely, abuse is immediately followed by "I love you" choruses. And in a particularly weird practice, people in the group sessions must signal their desire to speak by making the same arm-pumping gestures as a baby throwing a tantrum.

The film's distributor, Seventh Art Releasing, has made the slightly mondo pitch that "Over the GW" builds on the cult-world muckraking of its previous release, "Jonestown: The Life and Death of Peoples Temple," a documentary about '70s cult leader Jim Jones. "Over the GW" has a happier ending than " Jonestown" (it'd be hard not to). But it's too faithful to the discombobulation of its subject, which, ironically, limits its impact.

Through July 7 (155 E. 3rd St., between avenues A and B, 212-591-0434).