In the enthralling fourth episode of S Line, we find ourselves once again amidst the bustling streets, where Hyun Heup elucidates the mechanics of S Lines, leaving Han utterly astounded yet persistently inquisitive. Could there possibly be more than one pair of those enigmatic glasses? His curiosity piqued, Han ponders the overwhelming challenge Hyun Heup must face, her world permeated by those omnipresent lines.
Scene shifts to the school premises, where an assistant adorned with gold-rimmed spectacles endures a stern rebuke. Over lunch, she confides in her colleagues, unveiling heraspiration to tread the boards as an actor. Later, cloaked in a wig, she stealthily makes her way to the very hotel where Hyun Heup is moonlighting that weekend. Coincidence or fate? Hyun Heup's friends drop by for a casual hangout, just moments before the disguised assistant arrives, and they swiftly recognize her as a member of the school's staff.
Han's relentless pursuit of truth regarding his niece's mysterious incident leads him back to the pivotal moment of her personality transformation—the discovery of the glasses. He delves deep into the dusty archives of Hyun Heup's father's untimely demise, seeking clues. In a subsequent conversation, Hyun Heup confirms that Seon-a was not 'S-Line-entangled' with anyone in their class, adding another layer of mystery to the unfolding narrative.
As Hyun Heup tuned into the evening news, another murder tale unfolded, featuring a perpetrator adorned with gold-rimmed glasses, sparking curiosity—could this be part of a series? Post-school, Jun Seon swept Hyun Heup off her feet, leading her to a local pool for an impromptu hangout. Clad in their everyday attire, they plunged into the water, later warming up with steaming bowls of ramyeon. Hyun Heup regaled Jun Seon with tales of S-lines, her words believed without hesitation, for she seemed devoid of deceit.
In the hotel, the enigmatic wigged lady reappeared, her monologue filled with boasts of carnal conquests and voyeuristic pleasures from behind her glasses. Peering through the peephole, she caught a glimpse of her dashing colleague indulging in illicit liaisons with an actress next door. Overhearing plans for a rendezvous the following day, she lay in ambush, knocking out the actress upon her arrival and binding her in the room. Donning the actress’s gown, she stepped into her colleague’s embrace, reciting her script while clutching a stapler. As she attempted a nonchalant exit, he slumped unconscious.
With him inert on the bed, she confessed to poisoning his water. Staring at him through the mirror, she beheld blood trickling from his head, spreading across the linens. Rather than offering aid, she simulated intimacy while observing herself through the ceiling mirror, enacting her fantastical narratives.
Later, immersed in the bathtub, she began puncturing her arms and legs with staples, even her face succumbing to her self-inflicted artistry. The actress, having freed herself, stumbled into the hallway where Hyun Heup found her. Entering the adjacent room, Hyun Heup discovered the man lifeless on the bed, the assistant submerged in a tub, both surrounded by crimson pools. Han, summoned to investigate, noted the absence of glasses in the room. Hyun Heup hinted that those who wore such spectacles felt an inexplicable sense of uniqueness.
Returning to the grim scene, Han emptied the bloody bathtub water, uncovering the glasses beneath. Inevitably, curiosity got the better of him, and he donned them. Instantly, his vision was filled with ominous red lines, painting a picture of doom.
