Is Werner Herzog trying to do an Orson Welles? In 1946 the latter, saddled with a reputation for perfectionism, unreliability and artiness that poisoned the possibility of his being hired for studio directing jobs, agreed to make a conventional picture on time and within budget just to prove he could. The result was “The Stranger,” a thriller about a federal investigator tracking down a Nazi living secretly in America that’s efficiently made but shows relatively few truly Wellesian characteristics, and is dismissed nowadays as sadly uncharacteristic. Now Herzog, whose films have always been studiedly, even insolently, out of the mainstream, has made “Rescue Dawn,” a true-life tale of an American pilot’s escape from a Viet Cong POW camp in 1965 that seems far more direct and uncomplicated than his usual fare, with a triumphalist air that wouldn’t be out of place in a Vietnam-era version of “The Great Escape.”

But if this was Herzog’s effort to show that he could make ordinary movies, it certainly fails. “Dawn” may have a narrative that could serve as the basis for a slick, uplifting California blockbuster, but it’s filmed in an uncompromisingly gritty, naturalistic style that’s the opposite of studio chic. And it features performances by Christian Bale, Steve Zahn and Jeremy Davies that are hardly the stuff of Hollywood heartthrobs. Most important, like many of his earlier pictures it focuses on a wild-eyed protagonist obsessed with achieving an apparently impossible goal, usually involving overcoming the obstacles posed by a forbidding natural environment. In other words, it only partially strays from the writer-director’s past patterns.

Actually “Rescue Dawn” is a dramatization of a story Herzog had already told in documentary form in 1997’s “Little Dieter Needs to Fly.” The hero is Dieter Dengler (Bale), a German-born immigrant who joined the U.S. Air Force in the mid-sixties and found himself aboard an American carrier off the Vietnam coast. On his first bombing run—a secret mission over Laos—he was shot down, captured and put in a small camp with two other long-time American detainees, Duane (Zahn) and Gene (Jeremy Davies), the one a shambling, dejected fellow and the latter a tense, gangly guy. Along with three locals—Y.C. (Galen Yuen), Phisit (Abhujati “Meuk” Jusakul) and Procet (Chaiyan “Lek” Chunsuttiwat)—they’re brutally treated by a bevy of guards, including those they call Jumbo (Kriangsak Ming-olo), Crazy Horse (Yuttana Muenwaja) and, most ominously, Little Hitler (Teerawat “Ka-Ge” Mulvilai).

But Dieter’s a resourceful fellow, and before long he’s not only contrived a tool to loose the men from their shackles at night, but developed an escape plan, despite Gene’s misgivings. The plan actually works, at least to a degree, but the prisoners separate, with Dieter and Duane going off together on a long, arduous journey through difficult terrain to try to reach U.S. rescue squads, which—as we see here—will put themselves in danger to save a comrade and celebrate returns enthusiastically.

Herzog stages Dengler’s story with a gruff sort of integrity, refusing to buff it up and maintaining a near-documentary feel, not only in the grim prison sequences and the harsh jungle scenes, but in the bookending episodes aboard the carrier. And though he manages some moments of macho humor, he keeps the tone basically serious throughout. He’s fortunate in having the charismatic Bale in the lead—an actor who fills the part while being willing to thin down for authenticity’s sake (though not, happily, to quite the level of emaciation he achieved in “The Machinist”) and to undergo the rigors not only of scrambling through the wild and riding the river rapids but also of some pretty awful torture scenes. Zahn, abandoning his usual comic persona (though even a burly beard can’t entirely efface memory of it), complements Bale nicely as the pathetic, demoralized Duane, achieving real poignancy in his later scenes. Davies, as usual, overdoes the squirrelly act, though it could be argued that it meshes with the picture’s drug-laced period. Though some of the extras in the carrier sequences come on awfully strong, the locals in the supporting cast add a layer of strangeness and truthfulness. The technical work accentuates the realism—especially Peter Zietlinger’s cinematography, given the tough locations—and Klaus Bartie’s lachrymose score (supplemented with some classical excerpts) adds to the mood.

“The Stranger” didn’t make a great deal of money or change the studios’ attitude toward Orson Welles, and “Rescue Dawn” is probably still too idiosyncratic either to satisfy mainstream audiences or to convince anybody that Herzog’s the man for the next installment of “Harry Potter.” (Devotees of the director, on the other hand, may feel that he’s compromised his vision.) But Herzog’s rigorous, unvarnished approach carries considerable power, and it affords a showcase for another remarkable performance from Bale.