Set in a world inspired by pre-Shogun era Japan, this is a stunning debut fantasy in the vein of Grace Lin about how a young pearl diver goes to the ends of the earth to rescue her twin sister, who has been stolen by a ghost whale. 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 land scape, Kai must navigate encounters with scheming bandits, a power-hungry war lord, 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. Woven through with Japanese culture and legends, this many-layered story will grip readers of all ages.