Charting the divide between the haves and have-nots in a Swiss mountain town, Sister imagines the two as existing in fantastically separate spheres, joined only by the spindly wire of the cable car leading to an isolated ski resort. Above the slopes lies this idyllic paradise—a place of snow, hot chocolate, and nuclear families. In the shadows sits the sprawl of generically designed housing projects, marshy scrubland, and ribbons of cracked highway. The only thing passing between these two worlds is Simon (Kacey Mottet Klein), an adolescent Robin Hood with a hundred tricks up his sleeve, stealing from the rich to give to himself.
When Simon gets caught, as he does a few times in this scrappy, humanistic movie, the resort employees assume he's motivated by greed. Instead he's operating on a kind of hand-to-mouth motivation that their comparably cushy lives can't fathom; parentless and self-sustaining, he's also responsible for his wayward older sister, Louise (Léa Seydoux), who's more interested in attracting guys with sports cars than holding down a steady job. This upended family dynamic provides the impetus for the boy's illicit activities, which range from peddling stolen skis to pick-pocketing coats and filching from unattended lockers. Simon and Louise's relationship finds its apotheosis in an early scene where the boy finds a Charlie Brown-style Christmas tree in a field, then has to pick out another, even sadder shrub after his sister tactlessly drops trou and pees behind his first choice.
The film's ski-lodge scenes have the air of a dream, an impression that's further enforced by the sense of Simon as a constant interloper. By day he can feast on burgers and pretend his parents are off on the slopes, but come dusk he's forced to return to his Dardennian world of hand-to-mouth ruthlessness, sleeping in the living room of the tiny apartment he shares with Louise, sticking cigarette filters in his ears when she brings men home in the middle of the night. Comparing the adjacent lifestyles of holiday luxury and quotidian subsistence, director Ursula Meier considers the two faces of the modern Europe, a world in which surface prosperity continues to mask unseen poverty, even in its wealthiest corners. Simon may play with French kids, steal strange sandwiches from Dutch tourists, and make deals with English seasonal workers, but the promise of a united Europe has largely left him behind.
It's a reminder that you don't have to travel to the Caribbean to find context-free fantasy worlds stacked crudely on top of grinding poverty. DP Agnès Godard further conveys this divide through a spate of bisected compositions, contrasting the blinding brightness of the mountain, where views stretch as far as the eye can see, with the gray pallor of the lifeless lowlands, where the only thing worth looking at are those remote, inaccessible slopes. It's a visual style that comes off as a little obvious at times, an aesthetic that matches the often unsurprising arc of Simon's travails, which finds his network of schemes and feints crumbling just in time for the requisite surge of third-act pity.
Yet despite its predictability and somewhat shopworn narrative, Sister is sustained by a sturdy emotional engine and some intrepidly thoughtful characterization, factors which mostly make up for these weaknesses. A late revelation about Simon's parents, for example, seems destined to push things into melodramatic terrain, but instead leads to one of the most heartbreaking scenes of the year, with the suddenly vulnerable boy trading a heap of Euros in exchange for a simple embrace. The gutsy drive that defines the film's protagonist inevitably undercuts its attempts at drama (we know that whatever happens, a kid this resourceful is going to make it somehow), but that same self-sufficiency only makes the boy's fruitless search for love all the more tragic.