In this episode, the focus is on Percy, a 10 week old polar bear living in the Canadian Arctic. He was born during the winter in a den which was up to 40 degrees warmer than outside, where the temperature drops to minus 60 degrees Celsius and it is dark for months. Polar bears have thick coats, a 10 cm thick layer of blubber which acts like thermal underwear, and huge fur-covered paws which are like snowshoes. Polar bears are also hunters, and their paws have 20 cm long claws! They need to eat 2 kg of fat a day -the same as eight packs of butter! Percy's mum provides lots of nourishing milk and she forages over huge areas, sometimes covering up to 25 km a day. Hunting is a tough business in this vast white landscape and only 1 in 20 hunts are successful, but if mum can find a seal pup under the ice, it would be an excellent meal.