His parents were Midwestern Gothic: the father a bitter drunk who settled things with violence, the mother a poetic type who couldn’t lay off the booze. Yet in the way of strange, sad American stories, these two souls created a combination of DNA and childhood trauma that birthed one of the definitive actors—why not say artists?—of the mid-20th century. The son got his father’s name, Marlon Brando, an ideal moniker for an icon of bigger-than-life coolness and rebellious disdain. If you’re already up on Brando lore, and especially if you’ve read his oddball autobiography, this new documentary won’t uncover much that’s new. But it’s a pleasure to watch, serving up Brando as a model for other artists who aspire to sincerity and honesty in their work.