Once regarded as cuddly, chimpanzees seem downright demonic following the incident in Connecticut in which a pet ape destroyed somebody's face. Nim, the subject of this provocative documentary by James Marsh (Man on Wire), won't do much for the species' reputation, and it's even less generous toward Homo sapiens. Four decades ago Herb Terrace, a Columbia University linguist, took the infant Nim (full name: "Nim Chimpsky") and resettled him with the well-to-do family of Stephanie, his former student (and lover). The purpose: to teach Nim sign language and prove that chimps can use it to communicate. Inevitably, the experiment revealed more about the humans than the animal. As he grew older, Nim developed an Oedipal relationship with Stephanie. "It was the '70s," says the foster mom as she recalls how the ape explored her body. The story gets more absurd and sadder after that; and though Marsh's Errol Morris-like style can get glib, it never gets boring.