“Capurnaum” may be the dark horse in the Best Foreign Language Film at this year’s Oscars. But Nadine Labaki‘s picaresque drama about the undocumented, a Cannes award winner, stands apart as the most moving film in the field.

It’s built around one of those heart-stopping “natural” child performances that burn into the memory, even if the kid never makes another movie.

It’s about a boy growing up on the streets of Beirut. We don’t learn much about his background. He could be Palestinian or Syrian because however long his family has lived there, Zain has no birth certificate, no “papers” of any sort. He doesn’t even know his age, and his overwhelmed and distracted mother (Kawsar Al Haddad) can’t tell him if he’s 12 or 13.

Zain (Zain Al Rafeea ) was never enrolled in school. If he brings that subject up to his depressed, lazy father (Fadi Yousef ), Selim rouses himself from his many naps (when he isn’t impregnating Zain’s mother again) for a dismissive lecture.

“What do you want to go to school for? Keep working at Assaad’s.”

When Zain isn’t running fake prescriptions by pharmacists or selling tomato juice or what have you on the street with his sister Sahar, he makes deliveries for Assaad (Nour El Hussein).  Assaad lets the family — there must be ten or 11 of them — live rent-free in their apartment. Assaad sends extra food home with Zain because he fancies Zain’s sister.

Sahar (Haita ‘Cedra’ Izzam) is 11 years old. And the moment the streetwise Zain sees that she’s having her first menstrual period, he springs into action. He warns her about being “thrown out,” given away as he frantically scrubs her clothes and nags her to clean up and hide her status.

He starts questioning their parents, heated profane threats about what they might be planning, what they’ve done in such situations in the past and how he isn’t letting this happen to Sahar. But his plans to rescue aren’t far enough along to save her.

His mother lies to his face and his father hauls the little girl away to her fate as Sahar rains blows on his back, trapped behind him on his moped.

That’s why Zain runs away. That’s why, when we meet him, he’s in jail — a tweenage kid in stir “because I stabbed a sonofabitch” (in Arabic, with English subtitles).

“Carpernaum” is a linear flashback, with return trips to Zain in jail and in court. He has drawn the attention of the country by getting media attention for demanding that he be allowed to sue his parents. In court, he’s putting on trial those irresponsible, self-martyred parents, a “system” and a culture that created them and indeed caused Zain to be born into such circumstances.

Labacki, an actress (she plays Zain’s lawyer) turned director (“Where do We Go Now?”), has quite a story to tell in just the making of “Capernaum” (the name of an ancient Hebrew village, translated here as “Chaos.”). She paints this story in alternately picaresque and pitiful brush strokes.

Zain befriends an Ethiopian (Yordanos Shiferaw) waitress who takes him in. He winds up caring for her toddler as she struggles to earn money, get working papers and make a better life. Zain takes to this responsibility like the old soul that he is. Zain’s hilariously profane narration of Middle Eastern cartoons that they watch, his enterprising ways of caring for and feeding little Yonas — check out what he uses for a stroller — give “Capernaum” a lightness that belies the dark tale being told, the dire straits most everyone here is in.

Zain himself seems malnourished and small for his age. Everybody in this corner of Beirut is scraping by, and all these desperately poor people — again, many of them refugees — are being exploited at every turn.

For all the film’s early condemnation of poor people worsening their lot by having baby after baby, we get a taste of the parents’ circumscribed circumstances, too. They’re not raising their children at all, but is there a way they could have been anything but what they turned out to be?

Labiki isn’t above manipulating us as she lightly underlines the points she wants to emphasize, but she never lets “Capernaum” turn into a lecture.

And she gets natural, engaging performances out of one and all as lets us see cruel circumstances and the way some thrive in them, the desperation and despair of those old enough to see the doom they’re sentencing children to and the confusion and outrage of one extraordinary kid who is just now figuring out the game is rigged and that the future doesn’t exist. Not for him.

MPAA Rating: R for language and some drug material

Cast: Zain Al Rafeea, Haita ‘Cedra’ Izzam , Boluwatife Treasure Bankole, Yordanos Shiferaw

Credits: Directed by Nadine Labaki, script by Nadine Labaki, Jihad Hojeily Michelle Keserwany,  Georges Khabbaz and Khaled Mouzanar. A Sony Pictures Classics release.

Running time: 2:02