In Taiji, Japan, fishermen lure dolphins, about 23,000 a year, into a hidden cove and brutally harpoon them to sell their often-contaminated flesh as whale meat. Director Louie Psihoyos, aided by Richard O’Barry, a former dolphin trainer (he worked on the TV series Flipper), joins with other advocates (Heroes actress Hayden Panettiere included) to stop this barbaric slaughter of innocents. But first they have to risk jail to install hidden cameras and expose the atrocity to the world. The Cove plays like a thriller. It has the breathless pace of a Bourne movie, but none of the comfort of fiction. This is documentary filmmaking at its most exciting and purposeful.