S1, E4: Autumn, and the ice starts to return. As the first heavy snowfalls bury their young, the birds rush to finish breeding. Penguin chicks gather at the water's edge and following their departing parents and take the icy plunge. Leopard seals burst from the water to grab the unsuspecting fledglings. Storms ravage the continent; the seas begin to freeze over. Beautiful images of frost flowers, diamond dust and other optical effects describe the gradual formation of the ice. Further North, in the Sub-antarctic Islands, fur seal pups are beginning to swim and albatross chicks are fledging.