Ric O'Barry spent the 1960s training the dolphins that played Flipper, then spent the decades after trying to undo what that fame did to the species. The film follows him to Taiji, Japan, where a hidden cove becomes the site of an annual slaughter that the local fishing industry keeps off limits to cameras and outsiders. O'Barry teams up with free divers, special-effects artists, and underwater audio engineers to plant hidden cameras and microphones disguised as rocks, working at night to get footage the Japanese government and dolphin-hunting fleet have spent years suppressing. Interviews with marine biologists, activists, and former industry insiders lay out how mercury-contaminated dolphin meat gets mislabeled and sold as whale meat, and how the captivity trade at marine parks funds the hunts. The infiltration sequences play out with the tension of a heist film, building to footage of the cove itself, water turning red. It won the Academy Award for Best Documentary Feature.