Ji -wook, who finally discovered glasses in the bloody bathtub of aesthetic, admits that the words of Hyun -suk were true. Use the power of glasses to start an investigation into sexual violence in the runway. And I think that the person connected to the only one S line of Sun -ah is the culprit of the Sun -a case.

Hyun-heup, a girl who was born with the ability to see the S-line that indicates sexual relations. Because of this ability, Hyun-heup's family faces tragedy, and Hyun-heup becomes a reclusive loner for a long time. Then one day, a series of suspicious murders occur around Hyun-heup, and Hyun-heup uses his ability to see the S-line to track down the case...

Ji -wook finds out the truth about Sun -ah's S -line through glasses. Meanwhile, Hyun -suk, ahead of his 18 -year -old birthday, makes a big decision and meets the Jun -sun, which leads to an unknown confusion.

Ji-wook, who was continuing the investigation to find the culprit of the Seon-ah incident, hears about the S-line from Hyun-heup, but doesn't believe it. Meanwhile, Bang Ju-goo, an employee who lives in a goshiwon and dreams of becoming an actor, finds S-line glasses at Mi-seong's house and feels liberated, but soon after, he sees a woman connected to the music teacher he had a crush on and feels strong jealousy...