Kai and Kishi share the same futon, the same face, and the same talent for pearl diving. But Kishi is the obedient daughter, while Kai tries to push the rules, and sometimes they fight.

Still, when Kishi is stolen and killed by the legendary Ghost Whale, nothing will stop Kai from searching for her, deep in the ocean, hoping for a way to bring her back to life. But such a rescue is beyond the power of an ordinary mortal. Kai strikes a deal with the gods: she’ll steal a magic pearl in exchange for her sister’s soul.

As she journeys across treacherous landscape, Kai must navigate encounters with scheming bandits, a power-hungry warlord, and a legion of conniving fox spirits. And when a new friendship becomes something almost as powerful as her love for her sister, Kai must make impossible choices and risk everything just to get home again.