“The Black Balloon,” directed by Elissa Down, was inspired by her experiences growing up in a household with two autistic brothers, the younger of whom served as the model for Charlie (Luke Ford), a mute who communicates in sign language and heaving, wheezing grunts. When calm, Charlie is adorably playful and cuddlesome, but when agitated, which is often, he makes noises that assume a feral intensity.
At his most intimidating, during uncontrollable tantrums, he becomes a desperate wild animal, flailing and spitting and biting. Mr. Ford, who was seen earlier this year as the hero’s rambunctious son in “The Mummy: Tomb of the Dragon Emperor,” makes Charlie a character whose complexity transcends his disability; you can almost decipher the words he is unable to speak.
Ms. Down’s sympathetic alter ego is Charlie’s slightly younger brother, Thomas (Rhys Wakefield), a shy 15-year-old whose love for Charlie is increasingly compromised by his embarrassment. As the new kid at his school, Thomas is something of a fish out of water himself; barely able to swim, he struggles to stay afloat during lifesaving classes. He is so ashamed of Charlie, who attends a school for the disabled, that when Jackie (Gemma Ward), a sweet, attractive girl his own age, comes calling, he futilely tries to keep him out of sight.
“The Black Balloon” offers a wrenching portrait of the Mollison household. The boys’ exhausted mother, Maggie (Toni Collette), only days away from giving birth to a third child, refuses the bed rest