One January, in a cozy, snowy den, a polar bear gives birth to two tiny cubs. They weigh only a pound each, and they cannot see or hear.

After several weeks, the mother bear bursts through the den wall to give her children their first glimpses of the icy outside world. Then the family begins its journey- a 1,500-mile trek across the treacherous frozen landscape in search of food. Along the way, the cubs learn to hunt, swim, and travel so that when the time comes they will be prepared to venture out alone.