It's a question of balance that movies rarely get right. Either the lives they portray are too troubled, or they're too happy. Once in a blue moon comes a film that shows a recognizable human existence where laughs and pain, shame and kindness, love and anger are all knotted together in messy snarls. "The Black Balloon," a splendid Australian film about a teenager and his older autistic brother, gets it, from the happy/sad imagery of the title through the uplifting, but not saccharine, finale.

First-time filmmaker Elissa Down wrote the semiautobiographical script and directs with the assurance that comes from understanding a story on a personal level. There are indie clichés here, to be sure, but they're outnumbered by soul-piercing moments of insight and honesty.

When Aussie Army brat Thomas (Rhys Wakefield) and his family move to a new Sydney suburb at the start of the school year, he just wants to fit in. His self-consciousness is amplified by his chaotic family. His brother, Charlie (Luke Ford), expresses himself in grunts and sign language, behaves like an incorrigible toddler, and bolts for freedom whenever the front door is left unlocked. When their pregnant mother (Toni Collette) is ordered to rest in bed, their father assigns Thomas to brother-sitting duties. Mom, running on overdrive and relentlessly upbeat in the face of adversity, reckons that their family got Charlie because they're "capable." Still, Thomas can't help wishing that Charlie was normal. He loves his brother, but he's also embarrassed, frustrated and resentful. He'd just as soon keep Charlie a secret.

The film recognizes that in these circumstances, sometimes all you can do is laugh. When the unruly Charlie sprints through the neighborhood, Thomas must race after him, even though they're both in their skivvies. The chase ends in the bathroom of Jackie, the prettiest girl in class (Gemma Ward, an adorable blonde). Miraculously, Jackie sees the funny side of being interrupted in mid-shower, takes a shine to Charlie, makes a play for the delighted Thomas and becomes the family's fifth musketeer. But when Charlie's acting out triggers a bruising family fight, Thomas' chances with Jackie seem doomed.

Collette, an acting powerhouse, makes a strong impression as the boys' mother, ferociously committed to keeping Charlie a part of the family and never treating him like a hardship. The cast is strong top to bottom, and Ford impresses as the disabled boy. Writer/director Down is definitely a talent to watch, and "The Black Balloon" is a film to cherish.