A traumatic childhood experience leaves Cha Dohyeon, suffering from memory loss and dissociation. The latter has resulted in the creation of seven distinct personalities. Wanting to regain control over his life, he asks Oh Rijin, a first-year psychiatric resident, to help him, but she eventually falls in love with one of his personalities. Rijin’s twin brother, Oh Rion, a famous mystery novelist, investigates Dohyeon and his family.