America was on the verge of backing out of the Vietnam War in 1975 when President Gerald Ford made one last desperate P.R. ploy to stay involved by bringing 2,000 Vietnamese-born children to the United States in a chaotic mission termed "Operation Babylift." After bombing and poisoning the people of Vietnam for more than a decade, removing children from their parents was somehow seen as a humanitarian gesture. At least it made good prime-time propaganda, Uncle Sam and his helpmeets carrying orphaned children off airplanes and into welcoming American arms. Never mind that one plane crashed, killing 100 of those children en route, and that the U.S. government kept no real list of who, exactly, these children were. One problem stood above all the others: the Vietnamese children weren't necessarily orphans. Worried by rumors that Amerasian children fathered by U.S. military personnel would be killed after the war ended, and coerced by Americans who convinced Vietnamese women that their children could have a "better life" in the United States, parents gave up their kids, who, in cases like Heidi's, already had vivid memories of the families who had abandoned them.

The first war to be fought in America's living-room TV sets is still being dissected there, where archival footage is proving that one era's proudest moments are another era's sickest jokes. Mining the libraries of the major networks, Bay Area filmmakers Dolgin and Franco came up with the goods, evidence of American imperialistic hubris at work, and used the footage to connect the dots between the American Heidi and her Vietnamese roots. One sequence shows a sunglassed blond social worker seducing families into giving up their children ("I can take the children and send them to America ... and it's better for everyone ... other boy very happy"). Another pans a lineup of lonely kids being uniformly fed their bottles as they sit on a hard brown bench. Other images find the "babylifted" children devouring their airplane meals and falling asleep on one another's shoulders. Vietnamese children running away from bombs creates a backdrop for contemporary voice-over: "There were so many rumors, I was so frightened," Heidi's birth mom, Mai Thi Kim, says. "If you worked for Americans and had mixed-race children, they would be gathered up, soaked in gasoline, and burned." Says Heidi, "I was confused more than anything. I felt, 'Well, it must have been me, I must have been a bad child for her to give me up and not want me.' "

Mai Thi Hiep was seven when she was pried away from her Vietnamese family and put on the airplane she would later walk off of as Heidi. Her Vietnamese mother, like many women who gave their children up, believed she would be able to have contact with her daughter after Hiep became an American; Heidi's Vietnamese name means "united," her mother says in the film. But, in a nightmarish twist, while she was waiting two decades to hear from her birth mom, Heidi was being coaxed by her new mother to forget her past, perming her hair and keeping her Asian identity carefully under wraps. It wasn't until her adoptive mother – angry that Heidi had come home from a date 10 minutes late – dead-bolted the door to her home that, Heidi says, she "broke up" with her and began the search for her birth mom.

Dolgin and Franco don't consider themselves experts in international adoption, and when I recently spoke to them over the phone about making the movie, they had little to say about similarities, or differences, between the waves of children exported from countries fighting off the United States in one way or another over the years: Korea, China, Romania, Columbia. Says Dolgin, "This film was very focused on a family that we got to know very, very intimately." It was Dolgin's and Franco's histories with war – protesting it – that led them to Heidi's story. Dolgin's interest goes back to the '60s, when she was involved with the Newsreel film collective in New York and San Francisco and got involved with the People's Press. Franco, who was the director of photography on The Good War and Those Who Refused to Fight It, protested the war from Spain.

Some films about the Vietnam War have brought veterans back to Vietnam to heal their wounds. Others have brought veterans back to the United States to disintegrate. Many have opened up history for reexamination, and many others have glibly closed it shut. But the general rule on the Vietnam War is that it didn't produce happy endings. Heidi's is one story that was supposed to have one. Through a series of strange coincidences, Heidi found her mother and was going to reunite with her after 22 years and have an altogether new kind of American experience in Vietnam. The filmmakers only heard of the story from Dolgin's longtime friend from their anti-Vietnam War days, San Jose Mercury News reporter T.T. Nhu, a month before they were on the plane to Danang. They only met and interviewed Heidi the day before the trip. Their cameras naively followed where the story led with an innocence that allowed complete immersion. They didn't have time to do research on this kind of reunion.

But history is written into Heidi's face. In a hotel room inside Vietnam, just hours away from seeing her mom, she's using a curling iron on her bangs and telling the videographer she's applied waterproof mascara because she knows she going to cry. "I hope that they understand I'm 101 percent Americanized," she says. They soon will: A happy reunion devolves into a web of complicated miscues. Her Vietnamese family sees a wealthy American, well fed, well dressed, a "success story" who, they hope, will contribute to the family now that she's found them and give them a much needed lifeline out of their poverty. Heidi, recovering from her abandonment by this same family, experiences their requests as an affront and breaks down in full view of the assembled media – collateral damage, a second time. She leaves Vietnam unconsolably sad.

Documentarians have been feigning neutrality since the faceless style of cinéma vérité began, but this film really can't take sides, which is what makes it so incredibly fascinating. Though Franco says, "I could only think of a happy outcome; there was nothing that could prevent it from not being that way," it's the surprising discomfort that brings this film so far beyond others of its type. The audience, sympathetic to both Heidi and her birth family, is put in the position of mediator the same way the babylift do-gooders gone wrong were. It takes courage to make a film that feels this awful, and the audience has to admit its complicity in the wounds the United States still inflicts on Vietnam.

Heidi, whom the film leaves feeling at home back in the American South with a grandmother who only recently overcame her aversion to rice, still has not seen the movie. When the filmmakers finished the film in December, they sent her a copy, and she said maybe she'd watch it with her relatives and friends. When they called after the New Year, she still hadn't watched it. Then when they called her from Sundance, telling her they had won the Grand Jury Prize in documentary, she said, "Oh, congratulations. You guys worked so hard on it – I guess I should take a look at it."

Dolgin says Nhu, in conversation with Heidi, asked her whether they should go back together to try to fix things, and Heidi said, "Maybe I will." Says Dolgin, "It was her very polite way of saying, 'OK, get off my back.' " Perhaps it's time we did.