Flashback to the past. On a rooftop, Yoon-ho proposes to Soo-yeol that they kill each other’s fathers in order to end the misery they’ve been suffering. He reassures Soo-yeol that he’s stronger than he thinks, and oh dear, that’s the exact wording Joo-hyuk once used with Soo-yeol. I’m disappointed but not surprised.
Back in the present, K’s wracked with guilt as he admits that he clearly remembers his emotions at the time — he’d been overcome with the urge to kill the scumbag in front of him. Tears shine in his eyes as he says that he turned Soo-yeol into a murderer, and he asks Soo-yeol to catch Yoon-ho even if he’s gone. Soo-yeol collapses from the blood loss, and all he can do is watch K as he walks away.
Waking in a hospital to Hee-gyeom’s concerned questions, Soo-yeol asks for updates on Jung-hoon. They haven’t managed to track him down yet, though they’re currently questioning Sung-gwan. As for So-yeon, she hasn’t regained consciousness yet. Tentatively, Hee-gyeom asks Soo-yeol who K is, since he’d muttered the name in his sleep.
Cut to Soo-yeol in Geun-tae’s office, where Geun-tae informs him that K once came to visit in the middle of the night, looking tormented. Soo-yeol’s in disbelief that K, with all his heroic aspirations, killed someone. On the contrary, Geun-tae believes it’s possible, if K wanted to save Soo-yeol. K could have been a personality that the young Soo-yeol created in order to protect himself.
Downcast, Soo-yeol asks if this means K’s gone for good. It can’t be, he reasons, since Geun-tae previously said he wouldn’t disappear so suddenly. Geun-tae points out that it’s not that sudden, given that both men have changed a lot since.
Soo-yeol realizes that this could all have been part of Yoon-ho’s plan. Since Yoon-ho knows that he’s lost part of his memories, he could be manipulating him and distorting his memories to make him doubt himself.
Boss Yong meets with a drug distributor, who tells her that it’ll be difficult to sell her products to prospective buyers since there’s been so much police scrutiny on them lately. He’s angling for a discount, and he makes a veiled threat about how many people are after her. In response, she cracks the lollipop in her mouth, then smashes a wine bottle over the distributor’s head.
In the car, Boss Yong asks who the girl who took Pupil and committed murder was, and Andrei replies that he doesn’t think she bought the drug herself. With the increased police crackdowns, it’s difficult to obtain Pupil, so Boss Yong is suspicious of the mastermind’s motive behind specifically using their drug. It might be a ploy to get them to slash prices, so Boss Yong is determined to find out who that mastermind is.
Sung-gwan receives a visitation from a friend, and he tells him to hunt down Jung-hoon. He’s realized that there could be a connection between Jung-hoon and So-yeon.
In the hospital, Kyung-tae and Jae-sun are observing an unconscious So-yeon when Kyung-tae notices a figure that resembles Jung-hoon walking past. Kyung-tae gives chase, but he’s long gone.
Soo-yeol goes to visit Jung-hoon’s uncle in an attempt to obtain leads on Jung-hoon’s whereabouts, but to no avail. He gets into the elevator to leave, only for it to suddenly get stuck halfway down. It makes him recall the time when K confronted him in a malfunctioning elevator, and when the elevator resumes functioning as per normal, Soo-yeol lets out a dejected sigh.
As he’s about to get into his car, a motorcyclist in K’s usual garb drives past and parks. Soo-yeol runs up to him, elatedly grabbing him in a backhug, only for the motorcyclist to remove his helmet in annoyance — it’s not K, it’s an old man, ha.
Kyung-tae receives a call from the hospital staff, who informs them that a young man called to ask how So-yeon was doing. He traces the call to a payphone in Jung-hoon’s neighborhood, then relays this information to Soo-yeol.
Soo-yeol heads over to Jung-hoon’s house, where he realizes the police tape has been tampered with. He sneaks in, only to find two very bemused foreigners. Thus begins a hilarious sequence of Soo-yeol trying to arrest them in broken English, ha. He corrals them into a canvas wardrobe and zips it up.
Someone sneaks up on Soo-yeol from behind, but he reacts quickly, knocking him to the ground. It’s Soo-jan, the foreign thug from In-bum’s hired gang, and when Soo-yeol recognizes him, it sparks a flashback of the supermarket fight between Soo-jan and K. Upset that he’s made to remember K (and miss him all over again, aww), Soo-yeol yells in frustration.
Outside Jung-hoon’s house, a discarded food delivery bowl catches Soo-yeol’s eye, reminding him that Jung-hoon works as a restaurant deliveryman. He goes to check out the restaurant, entering via the back entrance, and he finds Jung-hoon asleep there.
He waits for Jung-hoon to wake, and when Jung-hoon tries to run off, Soo-yeol stops him. He advises Jung-hoon that if he stops here, he can turn his life around for the better, but Jung-hoon can’t fathom leaving So-yeon behind. Soo-yeol assures him that he’ll help So-yeon, then asks Jung-hoon who put them up to this. Jung-hoon’s tearful, clearly wanting to believe Soo-yeol.
Just then, the restaurant phone rings, and Soo-yeol goes to answer it. It’s Yoon-ho on the line, and he comments smugly that Soo-yeol looks terrified. Doesn’t Jung-hoon remind him of his past self? Soo-yeol runs out in a rage to confront Yoon-ho, but no one’s there, and by the time he returns, Jung-hoon is gone.
Sung-gwan gets released from detention, but Jae-sun and Kyung-tae show up to act as protection detail since Jung-hoon might target him again. Uncooperative and snarky, Sung-gwan disparages Jung-hoon, which fuels Jae-sun’s ire, but surprisingly it’s Kyung-tae that’s even more furious. Gritting his teeth, he bites out that So-yeon is still unconscious after Sung-gwan’s beating, then snarls that Sung-gwan better stay in his lane. Yes, you tell him! From afar, Jung-hoon witnesses this exchange.
Soo-yeol interrogates Sung-gwan’s friend, who quickly reveals Sung-gwan’s hiring of Soo-jan. That gives them the grounds to obtain a warrant, and they corner him at his house. However, he manages to escape, only for Jung-hoon to drive past on his motorcycle, knock him out cold with a metal pole, and take him away.
They’re headed to the neighborhood that So-yeon’s hospital is in, and Soo-yeol realizes that it likely isn’t a trap this time. On a rooftop, Jung-hoon beats up Sung-gwan with the metal pole, but Soo-yeol runs up and stops him before he can kill Sung-gwan. In tears, Jung-hoon pleads that he has to do this — X told him that if he fails again, So-yeon will die. Soo-yeol notices a hooded figure watching them from the nearby rooftop of the hospital, and he quickly gives chase, believing it to be Yoon-ho.
The hooded man manages to trip Soo-yeol up with a well-timed hospital cart, sending him crashing to the floor. He pins Soo-yeol down and begins punching him in the face. It triggers a flashback of young Soo-yeol being beaten up the same way in front of his dying father by a bloodstained Yoon-ho in a yellow raincoat, who grins madly that Soo-yeol helped kill his father first, so now he’s just returning the favor.
Meanwhile, a silhouette strides down the hallway, then pushes the door open — it’s K! Yanking Yoon-ho off a terrified Soo-yeol, he punches him till he sinks to the ground, then picks up the knife from the floor. We see that it’s actually Soo-yeol, calling Yoon-ho out for his perverse satisfaction in manipulating a child and committing murder.
In the present, Soo-yeol realizes that K didn’t actually kill anyone; rather, he saved him. The hooded figure picks up a scalpel, about to stab Soo-yeol, but his arm is stopped in midair by a gloved hand — yay, K is back! He makes quick work of the hooded figure, and Soo-yeol beams in relief to see K’s return. Looking like he’s shaken the weight off his shoulders, K introduces himself as Soo-yeol’s hero, Soo-yeol’s action star, and Soo-yeol’s K. Aww.
Returning to punching the hooded figure, Soo-yeol pulls his mask down to reveal his face, but it’s not anyone he recognizes. Just then, the hooded man’s phone rings, and Yoon-ho chuckles that just as he predicted, Soo-yeol had another personality all along. Yoon-ho’s watching him through the window from the ground floor, and Soo-yeol can only seethe as he watches him saunter off.
In the interrogation room, Kyung-tae tries to gently coax Jung-hoon, but he refuses to speak. The higher-ups order that Jung-hoon be transferred to the Juvenile Protection and Education Institution, so Soo-yeol drives him there, but decides to make a quick pit-stop for lunch.
Soo-yeol brings Jung-hoon home to a hearty meal prepared by his mother, and Dong-yeol comments on the similarities between Jung-hoon and young Soo-yeol. Quietly, Soo-yeol tells Jung-hoon that his name used to be Jae-hee, and that his father beat him up daily until he died and this family took him in. He reassures Jung-hoon that there are more kind people in this world than he thinks, which clearly strikes a chord in Jung-hoon.
Andrei reports to Boss Yong that he found a buyer, but there are still no leads as to how Young-joo obtained Pupil. Boss Yong isn’t willing to let all the unlikely coincidences slide, though, and Andrei switches to Russian to point out that Boss Yong doesn’t seem like she wants to leave the country all that much.
Hee-gyeom finds out from her friend that two people inquired about a ferry to Russia. He shows her a photo of Andrei and Boss Yong, and he tells her that Pupil is called the Eye of the Dragon in Russia — dragon, as in the yong in Boss Yong.
Hee-gyeom tails Boss Yong to the candy factory that acts as a front for the production of Pupil. Inside, Boss Yong gets a call from Andrei, who’s found out from the hooded man that Pupil was used in order to lure the cop that caught Gye-shik. Threatening the hooded man for the name of the mastermind, Andrei cuts off his finger, then rises to stab him, but someone sticks a syringe into his neck first.
The voice clearly belongs to Yoon-ho, but Andrei can’t see his face through the drug-induced haze. He swings wildly at Yoon-ho, only for the hooded man to stab him. Collapsing to the floor, Andrei ekes out for Boss Yong to leave without him, but Boss Yong yells in distress for him to tell her where he is.
She makes to rush after him, only for Hee-gyeom to break in at that very moment and tackle her. The two women fight, and Boss Yong demands for Hee-gyeom to tell her who the man they’re chasing is. Hee-gyeom responds with a punch instead, and Boss Yong fights back, eventually gaining the upper hand and cuffing Hee-gyeom to a table leg. Boss Yong runs out to save Andrei, leaving Hee-gyeom to struggle with her cuffs.
At the hooded man’s hideout, which is now cordoned off as a crime scene, Andrei and the hooded man lie dead. Soo-yeol’s in disbelief that someone could have killed both of them, and Hee-gyeom tells him that it’s the work of the man they’ve been chasing — Jung Yoon-ho.
Aww, Soo-yeol’s mother has prepared a lunchbox for Jung-hoon, which Soo-yeol passes to Jung-hoon when he visits him at the juvenile center. He unpacks the lunchbox to find that his mother only packed side dishes with no rice, which elicits a chuckle out of the both of them.
In the car, K worries that since Yoon-ho now knows about his existence, he’ll try to use it against Soo-yeol. He wonders if maybe it’s time for Soo-yeol to get rid of him for good, but Soo-yeol doesn’t seem keen on the idea.
Soo-yeol goes to confide in Joo-hyuk, who repeats his earlier conjecture that this is like a game to the mastermind. He offers to help in any way he can, and Soo-yeol confesses that he has a split personality. Joo-hyuk isn’t surprised, which he explains as him having had his guesses, and Soo-yeol says that he needs his help in treating his split personality. Noooo. Please tell me this is all part of Soo-yeol’s plan…
Flashback to Soo-yeol and Jung-hoon’s meeting in the detention center. Jung-hoon tells Soo-yeol that back when he discovered Young-joo and Joo-hyuk in the latter’s office, Young-joo had been crying. Joo-hyuk had spread his arms and exposed his torso for her to stab, all while she shook her head in protest.
Outside Joo-hyuk’s office building, Soo-yeol thinks back to the words Joo-hyuk has been telling him, which coincide with the words Yoon-ho used to say to him. He turns to glare up at Joo-hyuk, who’s watching him from his balcony, and his lips curl up in a determined smile.