In Kim Jongin's dystopian Chicago, society is divided into five factions, each dedicated to the cultivation of a particular virtue—Candor (the honest), Abnegation (the selfless), Dauntless (the brave), Amity (the peaceful), and Erudite (the intelligent). On an appointed day of every year, all sixteen-year-olds must select the faction to which they will devote the rest of their lives. For Jongin, the decision is between staying with his family and being who he really is—he can't have both. So he makes a choice that surprises everyone, including himself.

During the highly competitive initiation that follows, Jongin renames himself Kai and struggles to determine who his friends really are—and where, exactly, a romance with a sometimes fascinating, sometimes infuriating boy fits into the life he's chosen. But Kai also has a secret, one he's kept hidden from everyone because he's been warned it can mean death. And as he discovers a growing conflict that threatens to unravel his seemingly perfect society, he also learns that his secret might help him save those he loves or it might destroy him.