“Sister” screens at the Wisconsin Film Festival at noon Saturday April 13, at the Union South Marquee Theatre, and 4:30 p.m. Tuesday, April 16, at Sundance Cinemas. Advance tickets are available for both screenings. Visit wifilmfest.org for tickets and other information.

At first, the boy looks like any other on the ski slope. Decked out in a snow suit, his skis thrown over his shoulder, making chit-chat about the conditions on the slope. He could be the  youngest son in any wealthy and European family spending the holidays in the Swiss Alps.

And then we see him duck furtively into the chalet, into the locker room where skiers’ backpacks are kept. He rifles through the bag quickly, efficiently, and when comes across food, cookies or sandwiches, he stuffs them into his mouth like a starving man.

So begins “Sister,” a thoughtful and quietly wrenching drama from director Ursula Meier, one of several new Swiss films playing at this year’s Wisconsin Film Festival with assistance from the Consulate General of Switzerland’s Chicago office.

The boy is Simon (Kacey Mottet Klein), and he isn’t a tourist. He lives in town in a grubby housing complex with his sister Louise (Lea Seydoux). Louise is in her early 20s, but is basically a child, spending her days chasing after unsuitable men, and then relying on 12-year-old Simon to pick up the pieces.

In fact, Simon is the one keeping them afloat through petty thievery and cons, stealing skis and goggles off the slopes and then selling them to the next batch of tourists who come into town. He’s cynical and streetwise — young Klein gives an amazing performance — but his sister is his weak spot. He’s hopelessly devoted to her, even if its her irresponsible ways that keep them from getting out of that filthy little apartment.

Meier very deftly shows the two worlds of this Swiss resort — the rich tourists who blithely sail in and out, reveling in the beauty of the Alps, and the working-class townies who live below, oblivious to the mountains, focused on making just enough money to live on. Separating the two worlds is the gondola, which Simon rides to “work” each day, and becomes a symbol for the yawning gulf between rich and poor. Gillian Anderson, of “X-Files” fame, has a small role as a wealthy mother who Simon briefly cons, and as much as Simon wants to steal from her, it seems more important for him to have her affection, to be treated, briefly, like someone who belongs there.

Back at home, the relationship with Louise is much more volatile (and contains secrets we don’t learn until late in the movie). Louise is helpless, until she finds the next man she thinks will take care of her, and then all but ignores Simon. In one heartbreaking scene, Simon offers her a fistful of his ill-gotten euros if she’ll just cuddle with him for one night. It’s hard to know whether it would have been worse for her to take the money, or refuse.

But these two people are a family, somehow, and “Sister” ends with a beautiful, wordless final shot that symbolizes their bond, always linked, never quite connecting.