Yoon Se-ri and Captain Ri Jeong-hyeok take a stroll back home from the market. She tells him that he made her heart flutter back there and they call what he just did a pickup skill. Referring to him somehow finding her in the dark market using a candle. Captain Ri remembered what Staff Sergeant Kim Ju-meok said about Se-ri's heart hand signal meaning she likes him. He felt inclined to clear up any confusion. He informs her of his fiancee, but she cuts him off by saying she's not confused at all. She has many men in Seoul as well and that she's offended he had to draw a line. However, she's great at not crossing lines so he doesn't need to worry. Gu Seung-jun drives past Se-ri and Captain Ri walking after dropping off Seo Dan in front of Captain Ri's house. He immediately pulls over the car thinking he recognized the woman. By the time he gets out to check, they're already gone.
The women of the town see Seo Dan standing in front of Captain Ri's home and question her identity. She informs them that she's his fiancee and they're shocked before scurrying off. As Se-ri and Captain Ri approach his house she sighs in disbelief that he's been two timing with two fiancees. He reminds her he only said she was his fiancee cause he thought she'd be gone by now. She lectures him on how screwed they'll be if his real fiancee shows up. He confidently states it won't happen because she's studying in Russia. Right as they turn the corner they see his fiancee Seo Dan standing there. Se-ri whispers to Jeong-hyeok, "The trouble happened, right? So you were stupid, Mr. Ri. What are you going to do now?"
Seo Dan tells him she's been in North Korea for a few days and that she's here to pick up her uncles car that he borrowed. Captain Ri starts to explain who the woman next to him is, but Seo Dan just cuts him off. She suggests that he visit Pyongyang soon and they should have dinner with their parents. He offers to drive her back since the roads are dark and dangerous at night. Again, he explains that Se-ri is carrying out a mission with him and that she's a colleague. Seo Dan asks if they'll still be seeing each other after the mission to which Captain Ri says no. Se-ri agrees that once their mission is done they'll never see each other again so don't misunderstand. Seo Dan coldly replies that she doesn't care.
While in the car together, Seo Dan notices that Jeong-hyeok is still keeping an eye out to make sure Se-ri gets in the house safely. She asks him if he knows this is the seventh time they've met. They met four times with their parents and on the fifth got engaged seven years ago. She tells him that everything is in the right order except love is missing. She requests that he cooperates and she will do everything she can. He responds with a straight face that he'll try.
Jeong-hyeok gets dragged into Seo Dan's house by her mother and uncle. Her uncle is the General that lent him his car the last time he was in Pyongyang under investigation. The mother and daughter duo worked persistently to convince him to move the wedding forward. He spent the night checking his watch and trying to leave.
Gu Seung-jun can't help, but wonder if the woman he saw earlier was a doppelganger of Se-ri cause she looked similar. He thinks back on a time when they had dinner together. Se-ri informs him that although her second brother might have fallen for his background and academics, she will not. She has a feeling he's just laying out the groundwork and wants to marry her to have it all. She grew up in a tough family and has very sharp eyes. So she tells him to just get some pocket money from her brother and wrap it up. He can't help but smile remembering their interaction. He knows she's the smartest one in her family and wonders how she's doing.
Back at the house, Se-ri paces back and forth waiting for Jeong-hyeok's return. She hears someone at the front gate and walks out to see the women of the town gathered outside. They brought beer and snacks to comfort her after hearing what Jeong-Hyeok did to her. They gather in the inside angrily as they bond over calling Seo Dan swear words like gigabitch or asshat. They couldn't believe that Jeong-hyeok would have two fiancees. The more they drank the more the women wanted to shred him to pieces and demote him in the army. Se-ri tries to calm them down by explaining she's in love with him, but his parents opposition is a wall. The women feel even sadder for her for trying to protect the man that left her for another woman. She throws in that if Captain Ri gets the Preferential Star his parents may be more generous. During this time, wiretapper Jeong Man-bok was shaking his head thinking you really can't judge a book by its cover.
Captain Ri decides to visit his parents on his way home. His father pushes to have the wedding in the next year, but his mother tells them not to rush. Jeong-hyeok agrees to whatever his father wants, but requests for a big favor in return.
Jeong-hyeok returns home in the morning to see Se-ri sitting there. She created a line made of beer cans and tells him to think of it as the 38th parallel. Don't cross the line and there won't be a war. She calculates where he could've been all night when he said he'd be right back. She sits there with a knife held up while cutting an apple. He asks if she's angry and to put the knife down first. He explains he's planning to make her a member of the national team that participates in international track competitions. This will allow her to go to Europe by airplane. She'll be a reserve in case of injury so she won't need to participate. Once she arrives at the competition she'll go missing.
Since they have to go Pyongyang for a passport photo, she heads to the pawnshop to pawn her watch for money. She has to do her hair and get new clothes to avoid looking suspicious there. She notices an original designer watch that someone pawned and wonders if someone else must be in a similar situation as her. The shop owner says the man that gave it to him didn't even take money he just wanted him to keep it for him. Its been years, but he never came back for it.
Jeong Man-bok goes to Lieutenant Commander Cho Cheol-gang with the information he gathered listening in on Captain Ri and Se-ri. He tells him that Se-ri is going to disguise as a national team member and leave by airplane. Man-bok tells him that there doesn't seem to be anything suspicious going on because Division 11 members disguise themselves to leave the country all the time. Lieutenant Commander Cho asks him why is it they've never found Ri Mu Hyeok's watch? He reminds him that if that watch falls into Ri Jeong-hyeok's hands, they'll both be done for.
Captain Ri arrives at his unit to discover that his four main men from Company Five have been summoned by the State Security Department. Lieutenant Commander Cho threatens the youngest Private First Class Geum Eun-dong by letting him know only one of the four will live. If he talks, then he will live. He asks him, "What's the identity of the woman claiming to be from Division 11, why is she here, and what's Captain Ri hiding?" With tears in his eyes and a runny nose from crying, Private First Class Geum cleverly responds that he must be the last one of the four summoned and Lieutenant Commander Cho still doesn't know anything. He tells him he doesn't know anything either. Lieutenant Commander Cho calls him a sly motherfucker and hits him across the face.
Captain Ri appears and sees one of his men lying on the floor. He steps in between the two of them and tells Lieutenant Commander Cho that if he's curious about him he should just ask him. Captain Ri tells him to go and tell the truth about the things he's done. The phone rings in the interrogation room and the Senior Colonel is panicked asking Lieutenant Commander Cho why he's being summoned by the State Security Department about the truck incident that should've been taken car of already. Captain Ri takes his men and leave. As they're exiting the building he walks past Man-bok holding documents.
Company Five return to Captain Ri's house after all being severely beaten during interrogations. Se-ri apologizes to them for needing to cover for her. She doesn't have any money but can give them something else. She shoots them all finger heart signals as they sit there confused of why she's confessing her love to all of them. Later on Master Sergeant Pyo Chi-su says he's glad because he was worried she had indecent desires for Captain Ri. In a capitalist society even the heart has no backbone and is meaningless. Captain Ri continues sulking and pouting the rest of the night as he blames her lousy capitalist heart.
Man-bok hears from his wife that Captain Ri's fiancee chased away the kids harassing their son. She told their son that it didn't matter if his father was a rat. Man-bok responded that his job isn't very nice. After tucking his wife and son in, he stays up thinking nice years ago when he was getting beaten up by soldiers for being a lousy rat. Captain Ri Moo-hyeok scares them off and helps him up with a smile on his face. Man-bok curls up in bed crying as he remembers the incident clearly.
Captain Ri and Se-ri take a train to Pyongyang for the passport photos. Se-ri asks him if things will go bad for him if she disappears in Europe. Although his father warned him that even he can't help him if trouble happens, he tells her nothing will happen. She's relieved that things will be okay after she leaves.
The train stops due to a power outage and will take more than ten hours before starting again. As they look out the window Se-ri sees a crowd hopping salespeople running to the train. People are buying food, snacks, and even firewood. Once it's dark out, people start fires and enjoy their meals outdoor. Se-ri starts wanting blankets, corn, and everything she sees people with. Jeong-hyeok buys her everything, but asks her if she's planning to settle down there because she's being so greedy. Even so, he peels her a hot potato to eat as she calls him a good man. She tells him he'll be a great husband and dad in the future. He shares that he hasn't thought about the future because when things don't go as he thought he's left disappointed.
Jeong-hyeok thinks back to when he used to play the piano and when his brother passed away. Se-ri can see that he's had his heart broken by the past and tells him about an Indian proverb. "Sometimes, the wrong train takes you to the right station." She mentioned that she's felt like she's been on the wrong train her whole life and even wanted to jump off the train before. However, even now shes on a very wrong train as she laughs. He smiles at her comment. She wishes him the best even for after she leaves and hopes he'll think about his future. She hopes he'll arrive at the right station no matter what train he takes. She eventually falls asleep so he leans in to place her head on his shoulder. He wraps his jacket around her as she sleeps.
Se-ri's second brother captures Manager Oh, the man that setup Gu Seung-jun's hideout. They offer to pay him tenfold to switch clients and tell them where he's located. The assistant that watches over Seung-jun sets him up by agreeing to take him to Pyongyang to go to the casino for fun. They arrive at their hotel when Seung-jun notices some suspicious men at the front desk. He goes to his room and overhears the assistant on the phone trying to reach Lieutenant Commander Cho. Seung-jun puts a shotgun to his head as he confiscates the phone.
On the phone he speaks to Manager Oh before Se-ri's second brother grabs the phone and tells Seung-jun he's going to die after he give back the money. At that very moment, Seung-jun sees Se-ri and asks her brother if he knows where she is. He tells him she's dead and that they'll be able to meet in heaven soon. Seung-jun and Se-ri lock eyes as he pulls her into the elevator. Captain Ri stops the door from closing as he detains the man holding Se-ri's hand.