The documentary "Into the Inferno" sums itself up in its opening moments. A gliding helicopter shot takes us across the Vanatu Archipelago in the Galapagos, over waves of ground that resemble dried black pudding, until we see a group of tiny figures on the crest of a mountain. The camera draws close to them, eventually peering over their shoulders to reveal what they're looking at: a gigantic pool of magma. Then comes a succession of long shots of the magma. The film is hypnotized by it.
So are all of the people profiled in this movie, which is directed by Werner Herzog but credited as "A film by Werner Herzog and Clive Oppenheimer." Oppenheimer is a Cambridge volcano expert, or volcanologist, a slim man with a kind face and voice. He serves as the on-camera guide for Herzog, interviewing fellow volcanologists as well as people who spend most of their lives living or working near active volcanoes, including a woman who works at a monitoring station and a group of archeologists digging up shards of bone preserved by cooled and hardened lava. ("Every single piece of bone is a keeper," Herzog intones over footage of a dig site, one of many bits of voice-over that sounds a lot funnier when he says it.)