Tarnation is less a documentary than a shoebox full of found media objects—scraps of film, photographs, and music that Jonathan Caouette has been squirreling away since his preteens. Artfully splayed over digitized montages, together they storyboard Caouette’s indisputably horrifying life, and they do it without a whiff of self-pity. First, family snapshots and screen text document the involuntary subjection of Caouette’s mother, Renee Leblanc, to years of shock therapy in the 1960s. Home movies from the ’70s then make it clear that the therapy left her permanently mentally disabled. Still more text chronicles the travels of Renee with toddler son Jonathan, culminating in an episode in which, while living on the streets of Chicago, Renee was raped in front him. Owing to the unremitting agony of this story, you may easily forgive the visual anarchy with which Caouette tells it. Rapid-fire pastiches and music medleys take you through his youth in Houston’s punk scene, gay clubs, and foster homes. Then his unblinking camera delivers you to the present, where he has taken on the impossible charge of caring for his deteriorating mother. He plays the messages of breathless panic that she leaves on his answering machine, and, in one of documentary film’s most arresting scenes, he documents his own breakdown, as he sobs uncontrollably into the camera with worry and exhaustion. If Jonathan Caouette has not reinvented American documentary with Tarnation, he has done something very close to it. His avant-garde techniques are expressive, not experimental, and he seems to have made this for himself as much as for us. As a result, Tarnation wins itself sizable sympathy, precisely because it asks for none.