Hyun-heup, nace con el extraño poder de ver líneas especiales que revelan las relaciones íntimas entre personas. Este don sobrenatural trae desgracia a su familia y la condena a una vida de aislamiento.
Hyun-heup acude al instituto Bangju tras recibir un misterioso mensaje de texto. Allí se reencuentra con Seon-ah, una compañera de clase y sobrina de Ji-wook.
Seon-ah falls into a coma after a rooftop incident. Ji-wook, filled with guilt, works with Hyun-heup to find who's responsible. Jung-woo, a teacher, ends his engagement after seeing his fiancée cheat. Later, he finds glasses on his desk.
Ji-wook investigates Seon-ah's case and doubts Hyun-heup's S-line theory. Goshiwon resident Bang Ju-goo finds liberating S-line glasses at Mi-seong's, then feels jealous seeing a woman linked to his crush.
Ji-wook finds glasses in a bloody bathtub, confirming Hyun-suk's claims. Using the glasses, he investigates runway sexual assault cases and suspects someone linked to Sun-ah's S-line is behind her case.
