David Attenborough travels from the Arctic to the Antarctic to discover magical new ice worlds inhabited by the most extraordinary animal survivors on Earth.

Spring has arrived in the polar regions and male Adélie penguins arrive in Antarctica to build nests. In the Arctic, a polar bear mother hunts with her cubs. A woolly bear caterpillar emerges having spent the whole of the winter frozen solid.

Summer creates a window of opportunity that attracts hordes of visitors who cram a lifetime of drama into a few short months as they feed, fight and rear their young.

Polar landscapes are transformed as the big freeze returns. Most animals leave on epic journeys, some now battle to breed, and for the hardy few it’s a time of opportunity.

During winter most animals abandon the polar regions, but a few extreme survivors remain. This is the story of their strategies and battles to endure the planet’s harshest winters.

Humans have no natural protection against the cold of the polar regions so why have we been visiting these remote places for thousands of years and what keeps us going back today?

David Attenborough reveals how scientists measure the changes in the polar regions and what they mean for the animals and people who live there, as well as for the whole planet.