Inside an icy kingdom at the very top of the earth, a polar bear cub, Nanu, and a walrus pup, Seela, are about to tackle the brave new world that confronts them as their ancient ways of survival are about to change. The polar bears and walruses are surrounded by crystalline ice floes; shadowed by quick white foxes, hunted ring seals, watchful gulls, graceful narwhals--the “unicorns” of the North--and thick-billed murres that both fly through the sky and dive through the ocean. Guided by the instinctual wisdom of their doting, protective mothers, the cub and pup begin to explore their frozen world, where they discover a constant array of dazzling and surprising new experiences all around them. But as Nanu and Seela grow up, they will also develop the power and an indomitable will to survive. Polar bears and walruses have been born in a time when they will face not only the extreme natural conditions that their ancestors did, but also a growing new threat that could change the lives of future generations: the very ice that makes up their kingdom is literally melting away. Polar bears and walruses might be rivals in the wild, but together they now face a single danger. These two “giants of the North” are losing their beautiful icebound existence and must fight to seek out new ways to live in a world where the rules have changed.