Ula, a young humpback whale, is on the threshold of a new adventure. Every winter, Ula and her kin travel from the southern-most part of the planet to the warm waters of Tropica. It has been their way of life for centuries. Every winter brings excitement for new adventures, for in Tropica, Ula befriends dolphins, turtles and rays, who explore the continent with her. Kelp Crest Canyon and Nacre Labyrinth, in particular, are her favorite.

But not all is fun and games in the north. Though Ula has opened her heart to all the animals she encounters, she has faced cruelty in the hands of a few. She lands herself in a predicament, where she requires the aid of one who she has resented all her life. . . The humans. Thus blossoms an unlikely, but deep friendship, where Ula shows her human, Zoya, just how beautiful the wild can be. They spend a whole winter together, and Ula begins to change her perception of them.

But tragedy strikes. . . Something Ula was not prepared for. Sinking into an abyss, she sees no way out. It's the Dark Years all over again. Zoya wants justice, she wants to fight for Ula and her kin, but she needs their help. But the whales resent and distrust the humans for what they have done. If they don't put it aside and find it in themselves to trust Zoya, they may not live to see the next winter. . .