The word “utopia” was coined by Thomas More upon writing his book of the same name. Conjoining the Greek words “ou” and “topos,” the 16th-century English philosopher, lawyer, and statesman posited a society so perfectly realized that it could only be fictional — that is to say “no place.” As history has proved on repeated occasions, illusions have never been lacking in adherents, but when the chimerical nature of this or that utopia is ultimately unveiled to a true believer, the reaction can be sobering.

It happens in the harrowing new documentary from Madeleine Gavin, “Beyond Utopia,” and the results are heartbreaking. When the 80-year old matriarch of the Roh family, Sunok Park, thinks of the promises  made by the government of her native land — that would be North Korea — her face betrays a bewilderment so deep-seated that it is difficult to watch. 

Late in the movie, Sunok is being interviewed by the filmmakers with her daughter, Yeongbok Woo, at her side — that is, after they’ve fled from North Korea. A question is posed: Do you still think North Korea is the best? After some tense hemming and hawing, the older woman begins by sympathizing with Kim Jong-un and the challenges inherent to leadership. Yeongbok re-enters the frame and says: “Mom, don’t lie. When did Kim Jong-un ever give you rice to eat?” 

Sunok refuses to engage in any badmouthing or, rather, she is incapable of doing so. She does talk about the decision to defect from North Korea alongside her daughter, son-in-law, and two young granddaughters. Should she have remained, Sunok admits, the security police would have to be reckoned with on a daily basis and bribes paid. Still, she can’t bring herself to be critical: “So we must — we must really work hard to make Marshall Kim Jong-un even a little bit happy.”

Ms. Gavin provides a tersely stated history lesson of the era and then showcases examples of North Korean propaganda. In an undated black-and-white cartoon, hopping-and-bopping soldiers move in unison to destroy a large bomb labeled “USA.” The accompanying music is jaunty; the refrain, is less so: “Eliminate the American bastards … eliminate everyone.”

Cut to a defector from the North who is now an activist based at Seoul, Lee Hyeon-Seo: “In North Korea, we don’t have such a word: American. We only have ‘American-Bastard.'” 

Children learn math through story problems that involve the killing of Americans. They sing songs that iterate how “all human scum live in America.” Dismiss all of this as so much kitsch and then consider Grandma’s burgeoning amazement that the American filmmakers responsible for “Beyond Utopia” are not planning to kill her. They are, she says, “kind and nice.”

At the center of “Beyond Utopia” is Pastor Seungeun Kim, a defector, a Christian, and the spearhead of the South Korean equivalent of the underground railroad. Over the course of a decade, he has helped more than a 1,000 people escape from the North, earning the enmity of its government and putting his life at considerable risk. Notwithstanding a frame and demeanor that could be likened to that of a teddy bear, the good pastor is made of stern stuff, putting into effect escape plans of Byzantine complexity and utilizing intermediaries whose motives are decidedly un-Christian.

It is through these “brokers” of human life that much of the footage of the Roh family winding their way through jungles, safe houses, and various getaway cars was acquired. Other film was provided by family members, Pastor Kim and “Jiro,” a mysterious figure located in Japan who has posted unexpurgated photos and films of life in North Korea gleaned from cameras that he’s helped to smuggle inside its borders. This documentation is sometimes surreal, often brutal, and invariably tough-going. All the while, Kim Jong-un sustains a national mythology in which he is a Christ-like figure worthy of unquestioning supplication.

Ms. Gavin’s picture can’t be recommended enough even as it cannot be recommended lightly. “Beyond Utopia” is a difficult and important film.