FRONTLINE travels to Alaska to probe the growing battle between those who depend on the last great wild Sockeye salmon fishery for a living, the mining companies who are pushing for one of North America’s largest open-pit mines and the political framework that will ultimately decide the outcome.

The Bristol Bay region of southwest Alaska is home to the last great wild Sockeye salmon fishery in the world. It's also home to enormous mineral deposits - copper, gold, molybdenum - estimated to be worth some $300 billion. Now, two foreign mining companies are proposing to extract this mineral wealth by digging one of North America's largest open-pit mines, the "Pebble Mine," at the headwaters of Bristol Bay. FRONTLINE travels to Alaska to probe the fault lines of a growing battle between those who depend on this extraordinary fishery for a living, the mining companies who are pushing for Pebble, and the political framework that will ultimately decide the outcome.