Starring Zain Al Rafeea. In Arabic, with English subtitles. Rated 14A

Capernaum takes you deep into the slums of Beirut, where children suck back cigarettes, jump filthy puddles in their flip-flops, and face predators at every turn.

Nadine Labaki’s heart-ripping new film gives audiences a ground-level view of an ugly world they wouldn’t otherwise see. At its centre is tough, unaffected Zain (Zain Al Rafeea), a boy who may be 12, but he’s not sure: his parents can’t remember when he was born.

When the film opens, he’s in jail “because I stabbed a son of a bitch”. He’s soon led to court in handcuffs to sue his parents for giving birth to someone they had no means to care for.

In flashback, we learn he’s been raised in squalor, sharing a mattress with his four siblings. He and his 11-year-old sister Sahar find ways to survive in the streets despite abuse and alcoholism at home. But his world is torn apart when his parents consider selling Sahar to make ends meet.

Running away from that nightmare, Zain finds himself in a tawdry seaside amusement park, hooking up with an illegal immigrant, Ethiopian Rahil (Yordanos Shiferaw). He looks after her baby in a corrugated-metal squat while she scrubs floors and manages public toilets for money. When Rahil goes missing, they take to the streets to search for her, Zain pulling the infant in a big tin pot he’s mounted on a stolen skateboard.

Al Rafeea and Shiferaw ground Labaki’s empathetic story in beautifully natural performances. The scruffy-haired boy looks tired beyond his years, fiercely determined despite the weight he carries on his tiny shoulders. Rahil rarely speaks about whatever unimaginable torment she’s been through to get here, but transmits it in every painful gaze.

It’s not all unrelenting misery. Zain’s interactions with the baby can be funny, and his gentle care for her, as well as his affection for his sister, offer hope for the universe. With the kindness of Rahil, the misfits form a kind of family—and for a short while, it almost works.

Through it all, Zain is a beacon of resilience amid chaos. But at its heart, Capernaum is a plea for child welfare in the corners of the world where it doesn’t exist.