S Line keeps digging deeper—and darker.
Episodes 3 and 4 throw us straight into the thick of the chaos. What began as a unique supernatural mystery is now morphing into a tangled web of lies, power, and emotional fallout. The show wastes no time upping the stakes: from scandalous affairs and sudden deaths to eerie red lines ruining relationships, it’s clear that the S Line curse is spreading—and no one is safe.
With the glasses passing hands and more people becoming “seers,” the story cleverly explores how knowing the truth can both protect and destroy. Every episode feels heavier, more psychological, and far more personal. And just when you think you know where it’s going—another layer unravels.
Episodes 3 and 4 prove that S Line is not just about who’s connected to whom—it’s about how terrifying the truth can really be.
Quick Drama Facts
Title: S Line
Native Title: 에스라인
Genre: Mystery, Supernatural, Psychological, Thriller
Episodes: 6
Aired: July 2025 (ongoing)
Network: TVING
Director: Choi Hyeon-seok
Main Cast: Lee Soo-hyuk, Arin, Lee Da-hee
Plot Twist Element: The “S Line“—a red thread visible only to those wearing cursed glasses, connecting people who’ve had sexual relationships
Tone: Dark, eerie, emotionally intense
Streaming Availability: TVING (South Korea), Viki (International – region dependent)
Episode 3 – When Trust Turns Deadly
Episode 3 kicks off with a shocking moment—Kang Seon-ah falls from the rooftop, and Hyun-heup rushes her to the hospital. But the real bombshell? She was pushed by the English teacher she was blackmailing over a student affair. Soon, damning photos leak online, and the teacher is found dead with a supposed suicide note. But Detective Han Ji-wook smells foul play—and he’s right.
Meanwhile, Mr. Kim discovers a strange pair of glasses on his desk—yes, those glasses. With them, he can see the dreaded red S Lines. But when he notices that Lee Gyu-jin has no line at all, his unease grows. The glasses also reveal a painful truth in his own family, breaking his sister’s marriage apart.
The glasses expose dark truths—but at what cost?
Episode 4 – The Curse Spreads
In Episode 4, Hyun-heup tries to explain the S Lines to Ji-wook, but he doesn’t believe her—until he sees them for himself. Meanwhile, another teacher, Kim Mei-sung, becomes the next unfortunate wearer of the glasses. When she sees the man she secretly loves connected to someone else, it pushes her over the edge—ending in tragedy.
On the brighter side, Hyun-heup starts a new job and finally feels accepted by her peers. But that short-lived peace is shattered when more people begin unlocking the S Line vision.
The final moments are chilling: Han Ji-wook puts on the glasses and sees countless red lines tied to him. His mysterious past is now front and center.
Final Thoughts
Episodes 3 and 4 deepen the supernatural mystery while pushing the emotional stakes higher. From broken families to twisted jealousy, the glasses keep ruining lives—and yet, people can’t look away.
But the biggest enigma?
Lee Gyu-jin—calm, composed, and completely line-free. What is she hiding?