Summary We meet black bear cubs faced with a daunting climb down from their tree den and a mother sea otter nursing her fluff-ball baby through the chilly days of early spring. Stealthy 50-tonne sperm whales steal fish from the end of fishermen's lines in an extraordinary marine 'heist', grizzly bears grow big on a sudden wealth of salmon, and a huge male moose finds unlikely ways to impress a female. Thousands of bald eagles gather for a winter feast, and arctic foxes risk everything to find food in the alien world of an oil boomtown. People, too, must go with the flow of the extreme seasons, facing winter storms at sea to catch snow crabs, rushing across ice rivers with teams of huskies and taking advantage of Alaska's endless summer daylight to grow world-class giant vegetables. Surviving the bone-chilling cold, deadly blizzards and darkness of an Alaskan winter takes courage, cunning and remarkable endurance. In the raw beauty of windswept mountain peaks, icy tundra and snowbound forests, this is the story of the tough and resourceful characters that face up to the ultimate challenges of this untameable land.

• Documentary