Train: Episode 4
Finding himself in the parallel world, our hero seeks answers about the dead, the living, and himself. While largely familiar, a few unfamiliar elements of this parallel world drastically change the lives of our hero and the people around him. In this different reality, our hero uses his knowledge of his world to prove his innocence and learn about his alternate self.
As we take a ride down the train tracks, the show formally introduces us to the concept of parallel worlds. “Some scientists claim that a world just like ours exists because the universe expands infinitely. And they believe that a passage connecting the two world exists.”
Do-won runs out of the parallel Mukyeong Station, and he can barely process his utter confusion about his surroundings because he’s being chased by the police. He takes a turn onto the train tracks and freezes when he hears a gunshot in front of him. Slowly pointing his gun at his enemy, Do-won makes out a silhouette of someone pointing a gun at him.
His tense glare at his enemy softens with recognition, as he realizes that the person standing in front of him is Seo-kyung — alternate Seo-kyung, that is. He can’t believe it and drops his gun as he approaches her, unbothered by the gun against his chest. Do-won reaches out to touch her face and tears fall as he confirms she’s alive while alternate Seo-kyung watches him closely.
As Do-won gets transferred in custody, he pieces together what’s happening. He knows this isn’t a dream or a hallucination. He observes that the date and location are the same, but his surroundings are slightly different. The dead and living are also different, and he looks to Seo-kyung.
In the interrogation room, he sees Seo-kyung’s badge — her full name is the same, but her job here is a police officer. Do-won asks if she knows him, and she responds that everyone knows Officer Seo Do-won. Interesting, same job, different world.
Seo-kyung slides a photo of drug trafficker Lee Jin-sung and accuses him of murder. Prior to this murder, alternate Do-won was under investigation for an illegal drug charge with Lee Jin-sung as his supplier. Seo-kyung states that since they met three years ago, Do-won would allow Lee Jin-sung to avoid investigation in exchange for drugs.
Do-won doesn’t see how the evidence points to him as the suspect, so Seo-kyung continues. The night before, Do-won met Lee Jin-sung and visited his home, likely threatening Lee Jin-sung to take his side in the investigation. They presume that Do-won was not sober when he shot Lee Jin-sung with the 38-caliber that Do-won had in his possession until just now.
Determined to prove his innocence, Do-won argues that they’ve got it all wrong, starting with the motive. He claims that he doesn’t use drugs and consents to any bodily tests to prove it. He adds that they’ll know for certain that he isn’t the culprit when they compare the bullet from his gun with the one from Lee Jin-sung’s body.
As predicted, the tests and analysis prove Do-won’s innocence, which further confuse the officers and infuriate Seo-kyung. In his cell, Do-won wakes up from his dream about his nightmare-like past few days and finds Seo-kyung angrily pushing him against the wall. They didn’t find the ledger that Do-won claimed was in Lee Jin-sung’s possession, and she suspects that he may have lied.
Seo-kyung resentfully unlocks Do-won’s handcuffs and says that she’s ashamed that he’s a fellow police officer. She warns Do-won not to disappear since he’s still their prime suspect, and he assures her that he won’t leave. Even though he’s accused of being a murderer and suspects that he’s going insane, he promises to stay here. Do-won looks at Seo-kyung earnestly as she walks off.
At the train station, Do-won vows to himself that he’ll find a way to stay here for Seo-kyung. He looks at his hand as he remembers reaching out and touching Seo-kyung’s face. He sets out to figure out who he is in this world.
Frustrated with Do-won’s escape, Seo-kyung asks her team to send her all of their evidence tracing Do-won. She washes her face in the bathroom and recalls Do-won affectionately calling her name and touching her face. The interaction puzzles her and indicates that they don’t know each other personally in this world.
Do-won finds his home and goes upstairs to his attic room. He finds a key under a flowerpot and enters a cluttered room. As he cleans the room, he finds a photo of himself and notes that alternate Do-won attended police university. The light flickers, and he notices something under the light panel. He uncovers a box of needles, confirming that alternate Do-won could be a drug user.
Staring at the needles, Do-won wonders if his alternate self killed Lee Jin-sung and where his alternate disappeared to. He questions, “Same job, same workplace. But why did we live different lives?” He changes and decides to go to work, where his colleagues send him unwelcoming dirty looks.
In the cafeteria, Do-won eats alone and eavesdrops on the murmuring around him. He continues to eavesdrop on a conversation with his team member and other team leaders to fill in the blanks about alternate Do-won. One of the team leaders is especially disgusted by Do-won and brings up Do-won’s corrupt history from his last assignment. Then, the team leader mentions Do-won’s murderer father, who strangled someone with a necklace and smashed the victim’s head — the same M.O. of the murderer from his world.
As Do-won learns about how his alternate self is viewed, he sees Jin-hyuk exit the building. Jin-hyuk barely acknowledges him and walks away. Alternate Do-won is not liked here.
At his desk, Do-won looks through the files of the 2008 murder and learns that the exact same murder from his world happened here. Except in this world, his father was framed as the murderer. His investigation is interrupted by a resignation delivered by Jin-hyuk, who isn’t keen on sticking around under a corrupt boss.
Do-won asks if Jin-hyuk dislikes him because of his murderer father. Jin-hyuk understands that they don’t choose their parents and expresses frustration with Do-won choosing his current corrupt life. Then, he asks if Jin-hyuk believes that Do-won killed Lee Jin-sung, trying to gauge whether this Do-won is capable of killing someone.
Jin-hyuk asserts that anyone is capable of killing someone. He says that the distinguishing factor is the ability to resist the act. Do-won rips up the resignation letter and asks Jin-hyuk for some time. He needs to figure out if he actually committed the murder, and if he did, he promises to resign. Before he leaves, he asks if forensics specialist Lee Jung-min exists here.
At a crime scene, Seo-kyung lies down next to the body outline and looks over to see her father’s dead body. She approaches him and closes his eyes. Then, she turns on the lights, and we see that it’s Lee Jin-sung’s crime scene. She searches the apartment, and her presence surprises Jung-min (she exists!) as she enters the crime scene.
In this world, Jung-min and Seo-kyung don’t know each other personally, and Seo-kyung recognizes Jung-min’s name from Do-won’s call history from the day of Lee Jin-sung’s murder. When she calls this out, Jung-min explains that her job involves multiple calls with police officer every day, but that does little to defuse Seo-kyung’s accusatory tone because she knows that they’re not just colleagues. Jung-min claims that they’re childhood friends, but Seo-kyung knows the most recent update in their relationship. Apparently, Jung-min and Do-won are exes.
Seo-kyung knows that they stopped calling each other regularly post-breakup, which happened after Do-won’s corruption accusation at his previous station. She wonders why they happened to have called on the day of Lee Jin-sung’s murder and why Jung-min showed up at the crime scene after the initial investigation.
Jung-min accuses Seo-kyung of only searching for evidence against Do-won while leaving Lee Jin-sung’s side under-investigated. Seo-kyung responds that drug transactions are conducted discretely, so they don’t have any records. She adds that they’ve found no enemies, no financial issues, no family issues, or any relationship issues because he didn’t have a girlfriend.
Evidence in hand, Jung-min challenges Seo-kyung’s last point and shows her the hair clip she just found under the bed. Jung-min says that they found hair on Lee Jin-sung’s bed in their first sweep, and since his family is in Canada, the evidence points to a potential partner. She suggests that Seo-kyung redirect her effort in digging up her relationship history to reinvestigate Lee Jin-sung.
Do-won waits on the steps of the forensics lab and greets Jung-min when she arrives. He hopes that they’re friends here, and she tearfully calls him a crazy bastard. Do-won smiles in relief and asks for her help, since she’s the only one who’s on his side here.
Looking at the photos of Lee Jin-sung’s murder, Do-won recalls Seo-kyung’s accusation and asks Jung-min if he could have killed someone, since he’s known to be corrupt and use drugs illegally. Jung-min tells him to get a grip and reminds him that he called her on the day of the murder, insisting that he didn’t kill Lee Jin-sung. In a flashback, we see alternate Do-won in the bathroom stall calling Jung-min out of the blue and insisting that he didn’t kill Lee Jin-sung, though everything’s gone terribly wrong.
Jung-min knows that Do-won ruined his life in the shadows of his accused father, but she’s sure that he couldn’t kill someone. She shows him the hair clip and shares that there’s no trace of Lee Jin-sung’s girlfriend. It’s the same hair clip that the girlfriend had in Do-won’s world, and he recalls the girlfriend’s name: Park Min-kyung.
After her encounter with Jung-min, Seo-kyung looks into Lee Jin-sung’s call records and finds a repeating number that’s actually the last number in his call history before he was murdered. Seo-kyung looks up the number and finds that it’s a payphone.
Do-won meets alternate Park Min-kyung at her home and shows her a photo of Lee Jin-sung. She claims that she doesn’t know the man, and when Do-won shows her the hair clip, she doesn’t show any sign of recognition. Do-won notices that alternate Min-kyung is married with a baby on the way, and he leaves after her husband returns home.
As Do-won leaves the house, he wonders if Min-kyung doesn’t know Jin-sung in this world. Then, he notices something hanging from Min-kyung’s car rearview mirror. At the same time, Seo-kyung finds the surveillance camera footage of the last person to speak with Lee Jin-sung and notes the license plate.
Min-kyung accidentally cuts herself while cooking and tells her husband that she’ll get some air on the way to the pharmacy. As she turns the corner, Do-won appears and gets inside the car. He asks if her child is actually her husband’s child, and Min-kyung hysterically yells that she doesn’t know Lee Jin-sung.
Then, Do-won takes the USB hanging from her rearview mirror — the same one that Min-kyung in his world shared with him. He tells alternate Min-kyung that this USB holds Lee Jin-sung’s drug records and notes that she was the only one he trusted in this world too.
Seo-kyung also arrives and seems irritated that Do-won is there. She confronts Min-kyung about being the last person to talk to Lee Jin-sung before his death, and Min-kyung pleads that they keep this a secret from her husband, who doesn’t know anything. In distress, Min-kyung suddenly grabs her stomach in pain.
At the hospital, Do-won tells Min-kyung that he notified her husband and assures her that he didn’t tell him anything about her relationship with Lee Jin-sung. Min-kyung finally opens up and share that she wanted to end things with Jin-sung because the child belongs to her husband.
In a flashback, we see Jin-sung begging Min-kyung to reconsider and threatening to tell her husband about them. The doorbell rang, and Jin-sung asked Min-kyung to stay on the line. Over the phone, Min-kyung heard the scuffle and gunshot, and she confirms with Seo-kyung that she heard someone being slammed against the wall.
Do-won follows Seo-kyung, who turns to him and asks if he heard Min-kyung’s voice on the phone when he entered Jin-sung’s home. She suspects that Do-won found Min-kyung to threaten her, but Do-won calmly claims that he found Min-kyung to prove his innocence to Seo-kyung. She isn’t convinced and warns him that if anything happens to Min-kyung, she’ll blame Do-won.
We get a quick check-in on alternate Do-won, who’s alive and lying in a hospital bed. Meanwhile, Do-won returns to Min-kyung, who asks how he knew that this clip belonged to her. She wonders if Jin-sung would still be alive if she hadn’t called that night because he would have been asleep, and she wonders if he would still be alive if she hadn’t left him to marry another man.
Do-won thinks about the hypotheticals he agonized over — if his father had lived and were punished. He says that carrying or unloading her guilt is her choice. She asks what he chose, and Do-won responds that he carried his guilt and doesn’t intend on making the mistake again. Then, Min-kyung shares that Jin-sung told her something strange on the day of his murder.
Back on Jin-sung’s apartment, Seo-kyung collects a blood sample from the bookshelf, sure that this will prove that Do-won is the culprit. Continuing to retrace the evidence against him, Do-won goes the Ilsung Station, where he was reported to have met Jin-sung. Min-kyung told Do-won that Jin-sung claimed to have seen a dead body, and we see Jin-sung unzipping the suitcase, thinking it was his goods.
Shocked by the contents of the suitcase, Jin-sung scurried away but was met with alternate Do-won, who cornered him. Jin-sung became a witness to the sixth victim of this serial killer, and alternate Do-won had followed the suitcase and killer onto the train. Do-won pieces together that both Jin-sung and Seo-kyung were killed because they had seen the contents of the bag. Another update on alternate Do-won: he’s alive and awake! But in which world?
Do-won waits for Seo-kyung in front of the station and greets her by asking if she found evidence to accuse him. He takes the DNA test from her and sees that the test detected a woman’s DNA. Huh, curious. Seo-kyung says that this blood doesn’t belong to the murderer because she still believes that Do-won is the killer.
She asks how Do-won knew that Min-kyung and Jin-sung were having an affair, and he responds by pondering the possibility of a parallel world — where Min-kyung chooses Jin-sung and they also meet under different circumstances. Seo-kyung assures him that in a parallel world, they would still be ill-fated.
Seeking a fresh start, Do-won suggests that they recalibrate their relationship beginning with introductions. But Seo-kyung says that their relationship started 12 years ago, when Do-won’s father killed her father. Do-won looks alarmed that she knew about this connection, and it makes sense that Seo-kyung is so insistent on Do-won being the killer.
Seo-kyung finds Min-kyung waiting for her at the police station, and Min-kyung hands over the USB to her, per Do-won’s request. Before she leaves, Seo-kyung advises that Min-kyung keep her relationship with Jin-sung a secret to her grave. She says that there’s no such thing as universal good — only good for yourself so that you can keep living.
Seo-kyung’s team looks through the drug transaction records and comment that they’ve hit the jackpot. Seo-kyung seems less enthused and makes a call to ask about a transfer to Mukyeong Police Station.
At home, Do-won has a bad dream as a person limps upstairs to Do-won’s attic house. The person finds the key under the pot and unlocks the door. At the sound of an intruder, Do-won wakes up and quickly hides by his room door. He sees the back of an older man in the kitchen, and the man enters Do-won’s room.
Do-won grabs the man and holds him down on the bed, and when he sees the man’s face, he freezes. It’s his father. Do-won steps away in shock and repeats his observations about this world from earlier: “Everything is slightly different. The living are dead, and the dead are alive.”
Now that we’re into the parallel universe confusion, I’m intrigued by all the interesting tweaks that domino into completely different realities. The thought experiment that Do-won agonized over — of having his father properly charged for his crimes — is the reality in this alternative world, and now that he’s confronted with the consequences of that reality, I don’t think it provides any solace to Do-won. Other than the fact that Seo-kyung is alive, this world seems to have been tougher for alternate Do-won, and I’m curious to know more about the dominos that impacted Alt Do-won’s life.
Though Do-won is definitely reckless, he’s still principled. His conversation with Jin-hyuk was most telling about his commitment to justice, and I found Do-won approach to his investigation of himself in this world very wise and rational, unlike the wild Do-won we’ve seen previously. Maybe it’s the egregious wrongs of Alt Do-won that is making Do-won seem more principled, but I generally think that Do-won always knew right from wrong. He may be more behaved because he’s trying to redeem himself with Seo-kyung, but he has a long way to go before he can undo the 12 years of misunderstandings and false accusations.
After this episode, I’m inclined to believe that Alt Do-won isn’t bad enough to kill someone. There’s definitely another murderer out there, and the DNA sample (if it does belong to the serial killer) indicates that it’s a woman. Is that just something to throw us off? Or is that a hint? At first, I thought that maybe Alt Do-won was the one dropping off bodies in the Do-won’s world as hints, for their world to solve because the parallel world couldn’t, kind of like Signal. In the case of Signal, it was the past informing the future, and I think a similar theme applies here — one parallel world informing the dynamics of the other. I hope there’s more interaction between the two worlds and the two Do-wons (wait, wasn’t there another drama…), both informing the other about this interworld serial killer and giving Do-won and Seo-kyung the answers and closure they desperately need.