Destin Cretton’s Short Term 12, which won the grand jury prize for best narrative feature at this year’s SXSW, is a trip. It’s hard to tear yourself away from this story about a group home for troubled adolescents and the not much older staff tasked with caring for them. And it’s star, Brie Larson — who’s been popping up in supporting roles for a while, including in SXSW favorite The Spectacular Now — gives a career-making performance as the knowing but weary-eyed support staff leader Grace.

Cretton treads carefully over ground already overwrought stories of disparity, but his film never indulges in the temptation to over-dramatize the plight of its subjects. And it finds room to breathe and let flashes of humor and humility in, giving Short Term 12 its greatest sense of realism. In this story of building families from the pieces of broken ones, the moments of terror are leavened by the brief bursts of levity.

Grace (Larson) leads a team of twentysomethings, including her boyfriend Mason (John Gallagher, Jr.) at Short Term 12, a group home where the kids are assigned to their care until they age out of the system at 18 and are released. “You’re not their parent, you’re not their friend,” Grace warns the new guy on her staff. Even then you can tell Grace is hedging — when you look after wounded souls for so long, you can’t help but become attached.

When Jayden (a fantastic Kaitlyn Dever), alluded to be a victim of abuse at the hands of her father, moves in, Grace is reminded of her own childhood trauma and with news that her father is getting out of prison after 10 years, she’s slowly becoming unhinged. The scenes between Jayden and Grace are among the film’s strongest, intimating a special bond through soft nudges and wise glances. They don’t verbally say much to each other, but Cretton knows how to make their silence say plenty.

And really, Short Term 12’s greatest strength is communicating the ways it’s difficult for kids to articulate their feelings, problems and hopes. We never actually see much of the problems the kids in the home are dealing with, but as they find the only ways they can to express how they’re affecting them — through art, stories and toys — it proves more devastating.

Larson, who has played a lot of whip-smart teenage characters in her brief career, including in Diablo Cody’s short-lived Showtime series United States of Tara, is what makes this drama as effective as it is. She’s young, but she’s able to convey a world weariness and a sharp sense of wit in equal turns. And her scenes with Gallagher Jr. have just the right amount of sarcastic ribbing and tenderness.

It’s unclear when Short Term 12 will see a wider release, but after its successful world premiere at SXSW, it would be a shame for a story as affecting as this one to not be seen by more.