The real grabber in director Louie Psihoyos’ attention-demanding documentary is the tortured soul of dolphin trainer Richard O’Barry, a marine mammal specialist at Berkeley’s Earth Island Institute. After working on the TV show Flipper and arguably spawning a dolphin-captivity industry in aquatic theme parks everywhere, O’Barry has not stopped paying down the debt on his conscience. “The dolphin’s smile is nature’s greatest deception,” he says, as Charlie Chaplin’s bittersweet song “Smile” swims up through the soundtrack. Even if that makes you roll your eyes, you’ll still want to avert them during O’Barry’s tour of Taiji, Japan, where tens of thousands of dolphins each year are corralled into captivity or horrifically slaughtered and sold off as mercury-laden chunks of counterfeit whale meat. O’Barry and Psihoyos assembled an A-Team of activists, freedivers and audiovisual gadgeteers to sneak in there and gather incriminating footage, of which there’s just enough in The Cove to make you glad there isn’t any more. (Doubly so if you happen to represent Japan in the International Whaling Commission.) The movie is full of information and agitation, but it’s most alive in the wordlessly emotive moments, like when the harpooners light up cigarettes right after their kill — is that some twisted variation on a satisfied post-coital puff, or an attempt to calm their battered nerves? — or when we glimpse the guilt and desperation etched into O’Barry’s face.