Scarlet Innocence is a story about 20-year old Deokee whose quiet small-town life takes an exciting turn when a former university professor, Hak-kyu, moves in, fleeing from a sexual harassment allegation.
Mutual attraction leads to a lusty affair between Deokee and Hak-kyu, but when the fall semester begins, Hak-kyu returns to his family in the city. Deokee refuses to let the relationship die, leading to a tragic confrontation where Hak-kyu's wife commits suicide.
Eight years later, Hak-kyu, now blind and estranged from his daughter Chungee, befriends a new neighbor named Se-jung. Unaware that Se-jung is actually Deokee on a quest to destroy them, Hak-kyu gladly accepts her help and Chungee becomes attached to her.
This sets off a vengeance-fueled chain of events that ultimately brings the three bitter, angry, and desperate schemers on a twisting collision course with each other.