Sundance-winning documentary, framed as a real-life thriller, follows filmmakers as they sneak into 'The Cove' in Japan where dolphins are killed for meat. Crew captured process with cameras in fake rocks. Fishermen primarily use spears for slaughter, which turns cove's water red - earning film a PG-13 rating. And: Dolphin meat often peddled as higher-priced whale meat; hundreds of samples toxic with mercury, sometimes 5,000 times more than Japanese health advisory of 0.4 parts per million (click 'See also').