When Sorykah's twin babies are stolen, she leaves her job as engineer aboard an ice-drilling submarine in the frozen land of the Sigue to search for her children, for they, like her, are members of the gender-shifting Traders, a rare subspecies of humans that can shift from male to female and back again. Kasai's first novel creates a frozen world inhabited by permutations of humans and animals, from the eight-limbed octameroons to dog-faced humans and wolves who can become men. Despite the bleak images of a world too often tampered with, Sorykah and her alter ego, the male Soryk, demonstrate the strength and persistence of love and loyalty. Reminiscent of Ursula Le Guin's paradigm-shattering The Left Hand of Darkness, this piercingly moving story belongs in most fantasy collections.