It all begins with one emperor penguin jumping out of the water and doing a belly splash onto the ice. Then he rises on his little web feet and the rich, resonate voice of the narrator says: "Like most love stories, it begins with an act of utter foolishness. Each year at about the same time, the emperor penguin will leave the comforts of his ocean home and embark on an incredible journey. Though he is a bird, he won't fly. Though he lives in the ocean, he won't swim. For the most part, he will walk. But he won't walk alone." 

Gradually the scene fills with hundreds of penguins, padding along on their little feet, past immense ice formations under a crystal blue sky.

The destination is always the same, but the path is not, since the ice and land never stop shifting. New roadblocks will a…