As night falls in Antarctica, biting winds cast horizontal snow across the dark backs of a mass of huddled emperor penguins. The temperature is 50 below zero, the gales are 90 miles per hour, and the sun won't rise again for more than two months. NATURE captures these amazing - and well-dressed - flightless birds shivering on the ice as well as gliding through their most comfortable element, the water - a balmy bath compared to the air temperature above - where the emperors can hold their breath up to 20 minutes and dive a mile deep. Meanwhile, on the shores of Zavodovski Island, an active volcano, two million chinstrap penguins breed and travel on their own "superhighway" between the sea and their colonies on higher ground - taking care to evade the occasional 12-foot long leopard seal, which can consume six penguins in an hour.

Emperors and kings, chinstraps and Adelies - NATURE follows the penguins' difficult journey through the cycle of seasons and explores how a changing climate is affecting their habitat and survival.