On the cursed island of Envecor, everyone is doomed to wear their heart outside their bodies, and are immortal—unable to die, to change, to have children— until they find their soul mate. Paired soul mates are then turned mortal, freed from the curse, and able to leave. But all fairy tales have a dark side: those who don't want to lose their immortality pay "Heart Hunters" to find their soul mates and kill them so they may remain immortal. Psyche, a Heart Hunter, is hired by the king to kill his soulmate. As she sets out on her quest, she begins her own journey of mending her broken heart and learning to trust again.