Every autumn, polar bears gather on the shores of Hudson Bay in Canada to wait for the sea ice to form so they can begin their winter hunt. And every year, they are waiting longer. In one of BBC Two's most ambitious live broadcasts, Gordon Buchanan, Kate Humble and Simon Reeve head north to follow the remarkable story of not just these bears, but the entire Arctic. Vast and stunningly beautiful, the Arctic spans eight countries and six million miles of frozen ocean. As temperatures rise and the ice starts to melt, it has become an increasingly valuable battleground. Shipping routes are opening up. Oil, gas and minerals are tantalisingly within reach. Suddenly, the polar bears aren't the only ones on the hunt. Tonight, Simon travels to an unspoilt corner of Greenland that could become one of the biggest uranium mines in the world, while Kate follows the oil money that has shaped Alaska. In Churchill, Gordon learns how to stay safe when living side by side with the world's largest living land carnivore, and the team are live on the tundra to bring you the best of the bears.