It is the ultimate marine animal - one of the fastest, most powerful and most intelligent fishes in the sea. But it's also the most highly prized. Worth more than it's weight in silver, it's being fished to the brink of extinction. Now in an epic quest, 4-time Emmy award-winning filmmaker Rick Rosenthal plies the Atlantic and plumbs the secrets of the bluefin tuna. Narrated by Sir David Attenborough.