Life was perfect for Roz and her animals on the island. But when a mysterious and dangerous sea surrounds the island, the animals are forced to fight inland for dwindling resources.

Roz calms and organizes the animals, but the poisonous tides take a terrible toll on the island. So the wild robots, determined to stop the poisonous tide, set out on a journey across the sea. On the journey, Roz encounters amazing geological formations and incredible creatures, and sees the devastation that the poisonous sea can cause. Can the wild robot save the ocean, the island, and everything she loves?

This thrilling third installment of the Wild Robot series takes readers on a new adventure into the sea and the frigid northern seas where Roz may have to make the ultimate sacrifice.