How do you photograph a ghost? That's the challenge for wildlife photographer Paul Nicklen. The Great Bear Rainforest of British Columbia is the world's last big temperate rainforest. Black bears here have a genetic fluke that no others share: about one cub in ten is born white. Perhaps only a few hundred such bears exist. Paul's assignment is to bring back the most intimate portraits yet taken of a bear that few ever see: the ghosts of the forest.