Ace documentary maker Joe Berlinger (Paradise Lost, Metallica: Some Kind of Monster) anatomizes an ongoing, multibillion-dollar class-action lawsuit pitting 30,000 rural Ecuadorians against the Chevron Corporation, which has allegedly been dumping toxic waste into their sustaining length of the Amazon River. Eco-docs are bummers almost by definition, but here Berlinger’s superb explanatory skills compensate for any tax on the viewer’s conscience; what might have been a rote exercise in green sentimentality becomes a gripping, multifaceted thriller about media politics, global economics, and legal infighting. Wherever your sympathies fall, this may teach you a lot about the way the modern world works. 105 min.