How far would you go for love? When 16-year-old Cyrus discovers her childhood friend and crush, Soren, is possessed by a sinborn, a demon that feeds on the darkness in people's hearts, Cyrus knows she must do whatever it takes to save him. That means becoming a sineater, a person who consumes sinborns in order to purify them. But with each sin she eats, she risks losing her very identity. As she struggles to control her powers and confront her own darkness, Cyrus must decide how far she is willing to go to save the one she loves. Can she defeat the sinborn inside him and emerge victorious, or will the darkness consume them both?