Yoon Se-ri was on her way back to Captain Ri Jeong-hyeok's house holding the gift from the pawnshop. Two men appear in front of her with guns and put her into the back of a moving car. They call Jeong-hyeok and force her to say what they told her at gunpoint.
She tells Jeong-hyeok she left with Gu Seong-jun as planned so they don't need to say their goodbyes again. However, she couldn't resist telling him she loves him so the men try to snatch the phone from her. One of their guns accidentally goes off and Jeong-hyeok hears it. As he tries to call back the number and tries to call Seong-jun, they all go unanswered. Just then, he receives a phone call from someone telling him to get home immediately.
When Captain Ri arrives home, Lieutenant Commander Cho Cheol-gang and his soldiers are trashing his place. He's searching for the Division 11 woman and plans to use her to destroy Captain Ri's entire family. He'll probably need to torture her and burn her skin for information. Captain Ri couldn't stand it anymore and punch Lieutenant Commander Cho in the face before attempting to jump on him to hit him again. The soldiers grab Captain Ri and beat him before arresting him.
Company Five visits Captain Ri in the detention center. They update him on everything Master Sergeant Pyo Chi-su told Seo Dan's mother. Staff Sergeant Kim Ju-meok tells them that this is a classic South Korean drama move. Seo Dan's mother is rich and probably hired the men to kidnap Se-ri to get her out of the way.
Captain Ri realizes something and asks the comrades to reach out to Seo Dan for him. Seo Dan visits him and tells him he's being ridiculous because their wedding is in a few days and he's still concerned about another woman. He asks her directly knowing she has something to do with Se-ri's disappearance and wants to know who took her. She refuses to answer, but Jeong-hyeok guesses that she must've contacted his father. He tells Seo Dan to tell his father "if he hurts or harms her in any way, he'll lose the only son he has left for good." Seo Dan leaves him in there as the only choice she has if she wants to marry him.
Jeong Man-bok's son shows up at his workplace. He tells his dad that some men grabbed the pretty lady from the South yesterday and she dropped this box. Man-bok opens the box and discovers Ri Moo-hyeok's missing watch. He hides the watch and tells his son not to tell anyone about it.
Company Five executes a plan spread rumors that Captain Ri is the son of the Director of the General Political Bureau. The goal is to make it seem like it's a secret so others will overhear and pass the news around to help him get out. Ironically, Master Sergeant Pyo doesn't believe his family background but helps anyway.
Se-ri wakes up to find herself locked in a room with a camera watching her. She gets moved to a living room to speak to a man over tea. She tells the man he must be Seo Dan's father because his mouth, nose, and glaring eyes look just like her. Se-ri keeps going on about how this must be because she's in the way of their wedding. Jeong-hyeok's father, the Director, sits there amused but lets her continue talking.
Se-ri tells him that Jeong-hyeok hasn't done anything wrong because she threatened to report him that's why he helped her. He asks if that is all there is to their relationship. Se-ri responds that she likes him a lot but it's one-sided. She requests for help from the man to get her home safely since they both know Jeong-hyeok is just a captain with no power.
Jeong-hyeok's mother overhears the whole conversation and visits Se-ri in the locked room. She tells her to eat for strength and that it's not poisonous. Se-ri isn't sure who the woman is but asks her if she knows if Jeong-hyeok is safe. Jeong-hyeok's mother leads her to his room to sleep for the night. Se-ri realizes the room reminds her of Jeong-hyeok and this woman must be his mother. Se-ri spends the night looking through Jeong-hyeok's childhood photo albums and playing the piano in his room. She plays the melody that she heard when she was in Switzerland to soothe her mind.
As news spreads, the women of the town find out. The Senior Colonel's wife grills him for being so uninformed. She yells at him for ruining his connection to the Director by not treating Jeong-hyeok better. He runs out of the house to escape his wife's wrath. The Senior Colonel visits the detention center to get Captain Ri released. Captain Ri gets released and the Senior Colonel tells him to come to him for anything in the future. He invites him over for a meal since his wife his preparing one but Captain Ri asks for a favor instead. He requests for Company Five to be included in the emergency switch. This seemed like an odd request since it's winter and dangerous at the front lines so usually people avoid being picked.
Se-ri gets to spend some time with Jeong-hyeok's mother. Se-ri tells her that her son is very kind just like her. His mother was very pleased to hear that he's kind because at some point he's gotten very cold although he used to be kind. She grows fond of Se-ri and her personality.
Jeong-hyeok arrives at his parent's house and approaches his father in the living room. He asks his dad if she's dead and if he killed her. Jeong-hyeok tells his dad he'll be miserable and won't be able to breathe if something happens to her. His mother appears and tells her son to breathe and pulls Se-ri into the livingroom.
As Jeong-hyeok and Se-ri walk towards each other, Se-ri tells him he's never spoken so well before. Eyes are fully locked and it's like they're the only ones in the room. They apologize for putting the other through hardships as they wipe tears from each other's faces. His father watches from the sidelines in shock.
Later, Jeong-hyeok's father asks if yelling in his face made Jeong-hyeok feel better. Jeong-hyeok gives him his classic pouting face. Jeong-hyeok and Se-ri both took turns defending each other and taking the blame. Jeong-hyeok let his parents know that her threat didn't mean anything and that he by choice chose to help her because he was concerned for her safety. His father sighs at how unbelievable they are and tell them to get out of his sight. His mother invites them to a meal together instead.
Seo Dan meets Gu Seung-jun at a bar. She tells him the story of how a 17-year-old girl fell in love with Jeong-hyeok. He was a very popular boy in high school and all the girls loved him. She would walk past him from time to time, but she felt like they knew each other although they never spoke. Their families arranged the marriage and she flew to Switzerland to meet him. However, when she went to meet him, he didn't recognize her. He tells her that he's heard about her from his father and that it's nice to meet her. She tells Seung-jun it's not fair because she knew him first and liked him before Se-ri. Seung-jun calls her a fool because things like that don't matter. Seo Dan gets drunk that night and Seung-jun has to carry her home. Seung-jun carries Seo Dan into her place where her mother opens the door. Before she could talk to the man that carried her daughter home, he disappears.
Se-ri asks Jeong-hyeok if he wanted to be a pianist as a kid. She plays the melody she's been trying to figure out and asks if he recognizes it because no one else does. He asks her how she knows that song so she tells him she heard someone playing it in Switzerland by a beautiful lake. He sits down next to her and plays the song for her as he recalls the day he played the song at that lake. He wrote the song for his late brother and played it for the first and last time that day.
Se-ri tells Jeong-hyeok that she wished to die that day at the lake. She wanted to quietly disappear in a beautiful place without troubling anyone. But somehow he was there and without knowing it saved her life. He tells her to listen to him carefully and that tomorrow she will be returning home.
Lieutenant Commander Cho visits the Director of the Central Committee to convince him that the woman from the South is currently in the Director of the General Political Bureau's home. In hopes of catching them off guard with a search, they surprise visit his home. With an urgent investigation report, they send all of their men to search the whole property. After not finding anything Director of the Central Committee apologizes profusely and starts to leave. Lieutenant Commander Cho refuses to leave claiming that the South Korean woman must still be trying to escape and they have to go find her. The Director of the Central Committee slaps him for being disrespectful and have him dragged away.
Company Five gets summoned for an emergency company switch and as usual, Master Sergeant Pyo goes on and on about how Captain Ri must've been lying about his family background. First Lieutenant Park Kwang-beom has to enlighten them that Captain Ri will go to the front line with Se-ri and requested for the company switch. His team knows the area best to guide her back to South Korea.
Back in Seoul, Se-ri's mother and sisters-in-law enter her home. Her mother remembers the passcode to enter from the time she visited before. She came by back then just to tell Se-ri that her brothers aren't doing well so must she have such a successful company listed. She accused Se-ri of becoming successful just because she's greedy and wants to prove to her father that she's better than her brothers. Se-ri argued that it's her dream and she did it all on her own. Her mother tells her that she lives in hell thanks to her and that she doesn't deserve luxury. They can have a real mother-daughter relationship if Se-ri lets go of her greed.
Jeong-hyeok and Se-ri start their walk towards the DMZ border. They discuss a post-breakup condolences period. They agree on a six month period where they both won't date. Their meeting was fate from Switzerland to North Korea. He tells her to never feel alone because she has him even if he won't physically be by her side. He'll always want her to be happy until the end of her life.
They reach the border and Jeong-hyeok gives her some instructions on how to contact the rescue team. She asks him if he can walk her there, but he says he can't cross the line. As she cries crossing the line, knowing that it will be the last time they see each other, Jeong-hyeok grabs her arm from behind. He took a step over the line to kiss her lovingly under the night sky.