Strained relations between the Democratic People’s Republic of Korea (better known as the “axis of evil’s” own rogue state North Korea) and America frequently generate headlines. But a particularly bizarre and nearly unknown chapter in the nations’ acrimonious 50-year history is the subject of a remarkable and unique new documentary film by the British filmmaker Daniel Gordon.

“Crossing the Line,” which opens today at Cinema Village, tells the story of James Joseph Dresnok, a Virginia-born U.S. Army PFC who in 1962 walked off his post in the demilitarized zone that separates North from South Korea, and defected to the communist North.

“Comrade Joe,” as Mr. Dresnok was dubbed by the American press in the Cold War propaganda firestorm immediately following his defection, has remained in North Korea for four decades, a period in which both America’s curiosity and North Korea’s forthrightness about his status have waned considerably. “Crossing the Line” gives Dresnok the American traitor, Dresnok the communist hero, and Dresnok the twice-married aging alcoholic an opportunity to fill in what the second half of the previous century was like for him. “I think he realized that this was his last chance to tell his story and that this was how he was going to tell it,” Mr. Gordon said over the phone from a London cutting room.

Mr. Gordon is the veteran of two previous British documentary films set in North Korea. It was while shooting his fascinating 2004 film “A State of Mind” that he first heard that the all-but-vanished American defector was still alive and that “Comrade Joe” was in fact one of four American defectors.

“Someone e-mailed us and said, ‘Did you know that there are four Americans that live in North Korea still,'” Mr. Gordon said. “It turned out that two had already died, although there was never any official acknowledgment of that until we looked into it.”

During the year-long shoot of “A State of Mind,” Mr. Gordon and his associates made inquiries about the status of the surviving Americans. The communist bureaucracy didn’t bother to deny the defector’s existence, because the British filmmakers saw the men frequently. “They had kind of become propaganda heroes in North Korea,” Mr. Gordon said. North Korea’s movie-mad dictator, Kim Jong Il, had cast Dresnok and his fellow exiles in a 20-chapter propaganda spy film series begun in 1978 called “Nameless Heroes.”

“Every now and then we’d see them in one of these films because they only have five hours of TV a night in Korea,” Mr. Gordon said. The vintage clips shown in “Crossing the Line” from the “Nameless Heroes” series offer a unique glimpse into North Korea’s mutated communist popular culture. The crazy pulp-political storyline of “Nameless Heroes” (“They’re fantastic to watch until you have to sit through 20 parts,” Mr. Gordon laughed) boasts gun battles, romance, and torture scenes presided over by Mr. Dresnok, evilly laughing in an American army officer’s uniform. Though dubbed and subjected to all manner of vintage B-movie camera excesses, in “Nameless Heroes” Mr. Dresnok “does have a screen presence,” Mr. Gordon said.

In “Crossing the Line,” fascinating one-on-one interviews and contemporary footage of the 6-foot-5-inch, 64-year-old chain-smoking and shambling around Pyongyang show that Mr. Dresnok has a considerably distinctive and palpably awkward fish-out-of-water magnetism. “But it’s more than just a physical thing,” Mr. Gordon said. On camera in Mr. Gordon’s film, Mr. Dresnok, who by now has spent the majority of his life in North Korea, has a drawling 1960s Southern Virginia accent that has stayed trapped in the linguistic amber of the Korean he’s spoken for the bulk of his adult life.

Similarly, Mr. Dresnok’s ideas and attitudes do not seem to have progressed much past his “almost Dickensian childhood,” as Mr. Gordon said, as an impoverished orphan and foster child in the rural ’50s South, a formative period so brutal that the filmmakers were only able to find one other survivor of the final foster home Mr. Dresnok escaped by joining the army. Mr. Dresnok’s youthful exploitation appears to have set him up for an adult exploitation as a revolutionary “hero” who never fired a shot and has earned his exalted status (and additional food rations) by ignoring duty, not upholding it.

“He spends his whole childhood running away from authority,” Mr. Gordon said, “then runs to possibly the most authoritarian place on earth.”

If politics makes strange bedfellows, then defection, apparently, makes impossible ones. “Often in ex-pat communities, a guy that you would never normally hang out with becomes your best friend,” Mr. Gordon said. But Mr. Dresnok’s relationships with his three fellow turncoats, in particular with Charles Robert Jenkins, who returned to the West in 2002, were uniformly problematic.

“You’d think that in a country of 22 million North Koreans, four Americans could get on,” Mr. Gordon said, “and they just don’t. That was remarkable. Some of it was the North Koreans playing one off against the other. But the four would’ve been playing their own little power games as well.” “Have you ever made clothes for someone bigger than me?” Mr. Dresnok asks as he towers over his North Korean tailor. “Yes, I have,” the man replies with a smile, yet Mr. Dresnok’s narcissism turns the tailor’s words into an affirmative response. Like any child of serial abuse, the line between Mr. Dresnok’s self-love and self-loathing is a thin one. The persona that he has built during his four decades of exile, decades which “Crossing the Line” evenhandedly presents, is worthy of Werner Herzog’s delusional hero-victims. In “Crossing the Line,” Mr. Dresnok’s personality is so vivid because his character is as deeply flawed as his choices have been.