Wandering in the rain, the man looks like one of the walking wounded. His talk is obsessive chatter, looping back on itself, seizing on words and finding nonsense associations for them. He laughs a lot and seems desperately affable. When he sits down at a piano in a crowded restaurant, he looks like trouble, until he starts to play. His music floods out like a cry of anguish and hope.This is the central image in “Shine,” based on the true story of an Australian pianist who was an international prodigy.