No one who sees Short Term 12 will be surprised that writer/director Destin Cretton spent two years working in a group home for at-risk teens.

A riveting story about such a home, the film feels so authentic and emotionally on target that it's obviously the work of someone with first-hand experience. Short Term 12 is, in a word, real.

And painfully so. Based on Cretton's 2008 short film of the same title, Short Term 12 pulls no punches as it tells the story of Grace (Brie Larson), the twentysomething lead supervisor in a foster-care facility for kids whose worst enemies are their own families. All her charges are in a world of hurt, from Marcus (Keith Stanfield), a quiet but sometimes violent 17-year-old who's about to age out of the system, to Sammy (Alex Calloway), a perpetual flight risk who's more child than teen and who slumps into a deep...