In a lonely place: "Tori and Lokita"

You can feel the critics getting grumbly around the Dardennes, as if the realist aesthetic the brothers honed at the back end of the 20th century has diminishing value a quarter of the way into the 21st. Critics, as we know too well, value novelty above all else; we've grown equally restless around Ken Loach, another constant who's stuck doggedly to his social-realist guns. The trouble is that the issues of social inequality the pair's previous films raised haven't abated, and in most cases have only deepened as the century has gone on; so a rigorous attention to something like the plain, unsparing facts of the matter might well retain some worth, you'd hope. (In a diminishing landscape for art cinema, critics might equally cheer the fact the brothers haven't signed on for a Fast and Furious movie, even after the nerve-shredding chase scenes of 2005's The Child.) The brothers' latest, Tori and Lokita, looks to have been conceived in response to all those tabloid reports about migrants passing themselves off as someone other than who they actually are; yet rather than fan the flames of prejudice and fear, the film means to understand - and to help us understand - why someone might want to assume a fresh identity in the pursuit of a new life.

The names of these characters - closely-knitted young seekers who've come to Belgium from Senegal - hold up long enough to be enshrined in the title, but the film opens with a story (that the pair are brother and sister) which doesn't entirely hang together. They've barely the time to rehearse and perfect it, busy as they are with the kind of odd jobs - singing in a restaurant for cash-in-hand, couriering drugs - you take so as to survive the worst rigours of the asylum process and pay off those heavies who brought you to Europe in the first place. What we notice is how this hardscrabble way of life turns what are essentially children into little businessmen and women, haggling their way through curt, terse interactions where time really is money, because that money goes out as fast as it comes in. There is much getting by and making do, as there was in the Dardennes' Palme d'Or-winning Rosetta some twenty-odd years ago, only these title characters are offhandedly referred to as "the Blacks" by those who rely on Tori and Lokita to do their dirty work; they are several times more likely to be stopped on the street by police; and they are somehow even more expendable than Rosetta, when all's said and done. One further advantage of the Dardennes' constancy: it's a yardstick that demonstrates how much worse things have got for those at the bottom of the socioeconomic heap. 21st century? What 21st century?

Whatever form it takes, and whatever form it presents to the world as, all that's keeping these particular migrants from going under is their bond - and in the lead roles, newcomers Pablo Schils and Joely Mbundu do much to convince us of how much this pair need one another. The Dardennes' clear, close focus, their uncluttered line of inquiry - no unnecessary subplots, just an 88-minute fight for survival - allows us to notice such grave details as the shallowness of Lokita's breathing after she's separated from Tori and put to work as the live-in caretaker of an out-of-town marijuana farm. (The heart sinks anew as her handler gives unnervingly precise instructions on what to do in case of emergency.) All of a sudden, the film relocates from the hustle of the city to a lonely and perilous place; where once it was Tori and Lokita, now it's just Lokita, and a nagging residual fear of what Tori might be facing up to elsewhere, with no-one to pick him up after school or sing him to sleep.

There's a measure of thematic repetition in what follows (Tori becomes the latest in the Dardennes' gallery of kids with bikes), but it's that repetition that usefully underlines or drives points home (the bike's the one form of mobility this kid's got; it's what connects the social realists to the neo-realists of de Sica's age). And yes, the narrative is simple, even fable-like, but it permits for major effects, especially once Tori learns where Lokita's being held and vows to set her free, repositioning the film somewhere between Rapunzel and Prison Break. You clench whenever the skittish Tori tears headlong across a busy road; you gasp as a table is suddenly overturned, disrupting an otherwise placidly realist milieu, as violence does; and you wince as Lokita lands on the ankle crocked in the course of this haphazard escape bid. These are but small gestures for a cinemagoer to make, comfortable as we are in the darkness of the Picturehouse, but they bear out the empathy the film inspires, and are surely only more valuable - only more vital - when set against the callous-to-murderous indifference of this world's Priti Patels and Suella Bravermans. If the Dardennes' model of cinema ain't broke - if it still shatters your heart and makes you think - then why fix it? Wouldn't we critics be better off grumbling about those films that harden the heart and numb the synapses, the better to preserve a sorry status quo?

Tori and Lokita is now playing in selected cinemas.