It's the most popular fish in the American diet. From the school lunch box--to the high end sushi bar--to the outdoor barbecue, tuna crosses all demographic lines. We'll go fishing with the men who risk their lives to bring in a haul, stop in at Bumble Bee, the only major tuna cannery still operating in America, and visit the world's largest fish market in Tokyo, where a single tuna can sell for as much as $100,000. We'll also explore worldwide efforts to save the giant bluefin tuna, which has been over-fished to a point of peril. Then we'll head to sea with scientists who track the tunas' inter-oceanic migrations, and travel to South Australia, where entrepreneurs seek to breed the mighty bluefin in captivity.