'S Line' Episode 4 Recap & Ending Explained: What Does The S Line Mean Exactly? 

In S Line episode 3, we saw the consequences of knowing that someone is cheating. In episode 4, we see the problem with obsession. “Body Count” has always been a hot topic in the world, but S Line goes into the dark side of knowing people’s body counts and the sociological effects of it. Things truly get grittier this episode, with a stalking situation and more blood than we expected from this show. It’s also the most explicit episode of the show so far, which makes me wonder what’s coming next. This episode focuses on a new faculty member. It’s a woman who works in admin named Mi-Sung. As it goes, Mi-Sung is shy and meek at work, but she hopes to become an actress. She’s a woman who wears glasses, so everybody just assumes she’s not “cool” enough to be an actress. When someone is judged so much, they tend to start seeing the world differently, possibly causing trouble because of it. They change because of how they get treated and become confident in different ways. That’s what we see with Mi-Sung’s story. But with that, let’s jump into episode 4.

Spoiler Alert

What Does The S Line Mean? 

Episode 4 begins with Hyun-Hup telling Ji-Wook what the S Line means after he shows her Sun-A’s drawings. Hyun-Hup tells him about how, when people wear the glasses, they can see everybody’s body count via the red lines popping out of their heads. What Ji-Wook doesn’t know is that his own head is bursting with basically a cloud of red, but he’s going to find out soon enough. Hyun-Hup has been seeing these lines since she was born; she might be the only person who can see them naturally. But anybody who wears those special glasses that Sun-A had can see them too. The question is, are these glasses getting passed on from person to person? If so, who is passing them on? Last we knew, Hye-Young stole them, but now she’s missing, and the teacher she was sleeping with killed himself. Unless she murdered him and ran away? But there’s definitely more than one pair of glasses, because Mi-Sung was introduced in episode 3, and she was already wearing “S Line” glasses then, so they’re possibly not Jung-Woo’s glasses? 

Why Does Mi-Sung Go To The Hotel? 

In episode 4, Mi-Sung works a boring 9-5 in the administrative office at Hyun-Hup’s school. But, while outside school, she dons a pink wig and visits a motel where she practices lines on her own. It’s for her to “rest” and possibly improve her skills while she also watches other people have sex (yikes) through a hole in the wall. Interestingly, the motel is also called Mi-Sung (Jang). While I don’t know what this means, it’s an interesting coincidence for sure. The episode is also titled the same. Now, remember Hyun-Hup found a job ad in the previous episode? Well, she’s working as the receptionist at this motel. It is clearly not legal or safe for a minor girl to be looking after guests at a motel, but I guess anything for money. Kyung-Jin and Joon-Sun are eager to visit her there, and it’s quite nice to see her finally smiling at real people, rather than being concerned about the lines and their implications. Maybe she can be normal too. 

Meanwhile, Ji-Wook gets fixated on the glasses and also reads up about Hyun-Hup’s family’s case. It’s written in the file that she drew imaginary red lines to represent her dad’s affair. Ji-Wook then asks Hyun-Hup if Sun-A has any lines and if any of them connect to the guy she was having a date with on the night she fell. Hyun-Hup says she has one line, and that she doesn’t know who it connects to. She’s also been having nightmares of Sun-A dying. Meanwhile, while watching the news on TV, Hyun-Hup notices a criminal wearing the glasses, who also doesn’t have any “S Lines” of his own. 

Meanwhile, Mi-Sung meets the music teacher at school, and they have a basic conversation. He remembers her name, which makes her very excited. Much more than she should be. Mi-Sung and the teacher have one line each, but she imagines it being a line passing through both of them. On the other hand, Kyung-Jin leaves school early, so Joon-Sun uses the opportunity to spend some time with Hyun-Hup. He takes her to the swimming pool where there are no people because he knows she’s basically anti-social. She loves it immediately, and though she doesn’t know how to swim, she jumps into the pool because she can see blue in there and no weird red lines. It’s like she can finally look at the sky unblemished. They have ramyeon together after, and it could be possible that Joon-Sun is romantically interested in Hyun-Hup. She tells him about the lines, and he believes her without any judgment. 

At work, Dong-Sik asks Ji-Wook if he’s interested in anybody. He knows he’s the kind of guy who sleeps around. Ji-Wook is suddenly thinking about Kyu-Jin and her button (pfft, pervert), and he tells Dong-Sik there’s someone he’s thinking about getting to know, though he doesn’t want to sleep with her (shocking).

What Happens to the Music Teacher? 

Mi-Sung always takes room 205 when she goes to the motel. This is because there’s a hole in the wall through which she can see what’s happening in room 206. Another pervert is found. In the present day, Mi-Sung is shocked to see the music teacher in room 206. The same guy she’s been obsessed with and wants to sleep with. She notices that he’s with a woman who has been with many people before him. I’m not sure if this irks her, but I think the music teacher’s girlfriend is the kind of woman Mi-Sung wants to be, so she’s basically jealous in more than one way. Anyway, she watches them when they’re in bed together and then chooses to extend her stay so that she can replace the girlfriend the next day. 

The next day, when the girlfriend shows up, Mi-Sung hits her on the head with a fire extinguisher. She’s already drugged the water in room 206, so the music teacher’s in trouble before he knows it. Mi-Sung ties up the girlfriend in room 205, takes her clothes, and then goes into room 206, pretending to be her. When the music teacher realizes who she is, he gets scared and calls her a crazy woman. She doesn’t pay any heed to it. She simply narrates the piece of dialogue she had been practicing to him. When he tries to walk away, she throws her stapler (something she fidgets with all the time) at him, and then the drugs hit him too, so he falls unconscious in the bathroom. But I’m wondering, what if he hadn’t had the water? Then her plan would’ve flopped? Idle speculation, I guess. 

Next thing you know, she’s put him on the bed (though I don’t know how she managed that) and is kissing his unconscious face (yikes). She thinks he’s going to wake up soon and they’re going to sleep together, except copious amounts of blood start seeping out of his head and soaking into the white sheets of the bed. It looks like he must’ve hit his head in the bathroom when he fell. I can’t think of any other reason for such a thing to happen. Somehow, Mi-Sung thinks it’s the perfect time to “ride” him awake? I don’t actually know what to make of this bit, but she’s so desperate for him that she’d go to any length, I guess. Finally, she goes into the bathtub and uses the same stapler to kill herself. She staples herself all over her body and bleeds out (what?). 

At the end of S Line episode 4, the kidnapped woman falls out of room 205 and alerts Hyun-Hup to call the cops. Hyun-Hup goes into the other room and is shocked to see all the blood. When Ji-Wook shows up, the first thing he asks about is the glasses. Somehow, he can tell that this whole thing might be because of the “S Line.” Hyun-Hup can’t really help Ji-Wook in this case because the line between the music teacher and Mi-Sung didn’t merge. She has no answers for him. Hyun-Hup tells Ji-Wook that when people wear the glasses, they probably think of themselves as special, not realizing the deeper consequences of it. She reminds Ji-Wook that the glasses are dangerous because whoever wears them will most likely land themselves in a mess. This obviously piques Ji-Wook’s curiosity, and he ends up draining the tub Mi-Sung was in (wouldn’t this be the first thing?). He finally finds the glasses and puts them on (without washing them, ew). He thinks he’s doing this for his niece, but is he really? A detective with such power should ideally be able to do good, right? The next episode seems to be taking on a sexual harassment case, but I don’t think the “S Line” can help you understand the difference. So it will definitely be interesting to see how that is navigated. 

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