Polar bears gather in large numbers on the Arctic coast as they wait for the return of the ice. Soon tempers fray and violent sparring contests break out. Meanwhile two thousand beluga whales head for one special estuary, to thrash their snow-white bodies against the gravel and exfoliate – it’s a gigantic ‘whale spa’. Inland, the tundra undergoes a dramatic transformation from green to fiery red. Here musk ox males slam head-first into each other with the force of a car crash at 30 mph, as they struggle to defend their harems. Frisky young caribou males play a game of ‘grandma’s footsteps’ as they try to steal the boss’s female. Down in Antarctica, Adelie penguin chicks huddle together in crèches. When a parent returns from fishing, it leads its twins on a comical steeplechase – sadly there’s only enough for one so the winner gets the meal ... Two months later and the chicks are fully feathered apart from downy Mohican hairdos - they’re ready to take their first swim … reluctantly – it seems penguins are not born with a love of water! And with good reason - a leopard seal explodes from the sea and pulls one from an ice floe – a hunting manoeuvre that has never been filmed before. As winter approaches, and everyone has left, the giant Emperor penguin arrives and makes an epic trek inland to breed. The mothers soon return to the sea leaving the fathers to hold the eggs and endure the coldest winter on earth.