On Ido, island of Sphinx people, cocooned cities, and Mer Ancestors, love and monogamy are strictly prohibited, physical pleasures abound, and a brewing civil war pits youth and virility against age and experience. The Ido Youth seek the preservation of Taste, a set of carnal sex rites beginning in the 21st year and ending with climax, Enlightenment, and Elderhood. Meanwhile, the Elders vow to obliterate the old traditions in favor of The One Faith, a religion of love, marriage, restraint, and discipline under the direction of a mysterious foreigner known simply as, The Guide. At the center of the war is Onya, esteemed warrior and daughter of the shrewd Elder General Dame. Though dedicated to both Taste and tradition, she begins to question the very core of her beliefs when she falls in love with Quince, co-General of the Youth Cause. Together they must navigate otherworldly pleasures, the savagery of war, an intrusive religion, and their own forbidden love.