Released year: 2025
No of episodes: 6
Main Cast of S Line:
Lee Soo-hyuk – Han Ji-wook, detective investigating the S Lines.
Lee Da-hee – Lee Gyu-jin, mysterious teacher with no S Line.
Arin – Shin Hyun-heup, student who can see S Lines.
Lee Eun-saem – Kang Seon-ah, Ji-wook’s niece and Hyun-heup’s classmate.
Kim Dong-young – Oh Dong-sik, Ji-wook’s junior detective.
Lee Kwang-hee – Joon-seon, class president with a crush on Hyun-heup.
Episode Summary:
In episode 1 of S Line, Although the premise and opening of the new K-drama S Line are undoubtedly R-rated, the show nearly feels more like a social experiment on the surface. What does the term “sex line” actually mean? One man and one girl, who wear special glasses, are the only ones in this show who are able to see people’s sex lines. Now, what precisely does this mean? It’s the crimson line that appears from an individual’s head, connecting them to everyone they’ve been intimate with. Meanwhile, Detective Han Ji-wook starts looking into the case, and the enigmatic S Lines begin to intertwine their destinies.
Episode 1: Girl Wearing Sunglasses
Shin Hyun-heup is a high school girl who lives alone in the dark, keeping her windows covered. She can see strange glowing red threads, called S Lines, above people’s heads. These lines show who has been in a sexual relationship. She has seen them since birth, and this ability has only brought her trouble. As a child, she once drew the lines she saw, which led her mother to discover her father’s affair and in anger, her mother killed him. Since then, Hyun-heup has avoided people and tried not to open her eyes too much.
One day, she peeks through her window and sees a man with many red lines trying to lure a schoolgirl into his car. Across the street, she also notices a woman vaping who has a few lines above her head. Hyun-heup knows that some things in life are better unseen. Sun-a, on the other hand, is bullied at school and is forced to compensate her tormentors. She doesn’t tell Ji-Wook what caused her injuries, though, when he sees them at home. Instead, she tells him that she needs money, to which he responds that he isn’t an ATM. Although the cause of her parents’ deaths is unknown, Sun-a is probably an outsider due to this and the fact that her uncle works as a detective. Moreover, Ji-Wook discovers that his father is standing on the roof when he receives a call at work regarding him being in the hospital. It is obvious that the family has some trauma to get through.
While at home, Sun-a finds a set of glasses. When she wears them, she sees a luminous red line rising from her own head. She becomes anxious and attempts to touch it, but it’s impossible to do so. when Ji-wook gets home, she observes him through the glasses and is astonished to see endless lines above him. Filled with fear, she sprints out of the house.
Sun-a skips school and asks her uncle for money to pay off the bullies. Han notices her bruises but she refuses to talk. Later, Han notices Hyun-heup’s apartment window and hears there was a police report from her building. He visits her, but she quickly shuts the door after explaining her mistake in calling the police.
That night, Hyun-heup sees the man with one line again this time attacking her neighbor. She tries to go help with a knife, but she is terrified to step outside. She finally runs over, but the man, Jeong Min, takes the knife and stabs her. Detective Han, across the street, sees her apartment door open. He goes inside, finds her S Line board, and spots the attack. He rushes over and shoots Jeong Min before he can stab her again.
Before dying, Jeong Min says the lines are disappearing. Hyun-heup suspects his glasses let him see S Lines too. Later, she gets a strange text from someone claiming they can see what she sees, inviting her to meet. For the first time in years, Hyun-heup steps outside unsure what she will find next.
Episode 2 :Is Sun-A Dead?
Episode 2 is probably set some time after the stabbing because Hyeun-Heup seems to be getting better. She is headed to Ark High At school, Sun-a is once again bullied by her classmates. But this time, their teacher, Lee Gyu-jin, suddenly steps in and stops the fight. She grabs the bully by the hair and warns her to leave Sun-a alone. This shocks everyone. Even stranger, unlike others, Teacher Gyu-jin has no S Line above her head at all, making her different from everyone else.
At home, Sun-a finds a pair of glasses. When she puts them on, she sees a glowing red line rise from her own head. She panics and tries to touch it, but it is impossible. Later, when Ji-wook comes home, she sees him through the glasses and is shocked there are countless lines above him. Frightened, she runs out of the house.
The next day at school, Sun-a notices that her bully Hye-young has an S Line connected to a teacher. Curious and angry, Sun-a follows her and sees Hye-young go into a motel with that teacher. She secretly takes a photo and shows it to Hye-young, but the bully laughs at her. This won’t affect me,” she says. Only the teacher will be in trouble.
On the rooftop, Hye-young once again tries to corner Sun-a. But this time Hyun-heup arrives. She grabs Hye-young by the tie and warns her that if Sun-a falls, she will fall with her. The bully gets scared and cries for help. For once, the power shifts.
Even after being saved, Sun-a feels upset and pulls away from Hyun-heup. She doesn’t thank her, still hurt by everything happening around her. Hyun-heup doesn’t mind she knows Sun-a is struggling.
Detective Ji-wook continues his inquiry. He queries Teacher Gyu-jin about another instructor who could potentially be connected to these matters. By the end of their discussion, he perceives that her blouse button is undone. This detail seems odd to him, raising a question in his mind: is Gyu-jin being careless, or is she hiding something?
As the day ends, Hyun-heup steps further out of her shadows, Sun-a becomes more deeply trapped in secrets, and Ji-wook starts to sense that the truth behind the S Lines is darker than he imagined.
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