Mousetrap Ending Explained: Who is the Real Moon-jae?

The psychological thriller series ‘Moustrap’ charts the story of a unique kind of torment where a man’s name, life, and face are stolen from him. Known for his reclusive, anti-social lifestyle, author Je Moon-jae hasn’t left his apartment at all in the last three years. However, his apartment, along with everything else he owns, is taken from him overnight when he wakes one morning to find that his identity has been stolen. A doppleganger, known only as the Rat, has overtaken his entire life and has the world convinced that he is the real Moon-jae.

In light of this world-shifting event, the real Moon-jae has no one to rely on except for Noja, a loan shark who has an old debt to settle with the author. Somehow, the two agree to work together, embarking on a mission to prove the Rat’s sinister scheme and restore the other man to his old life. Yet, as the story progresses and the Rat begins to step away from the shadows and into the daylight, it becomes more and more difficult to confidently conclude who the real Moon-jae is. SPOILERS AHEAD.

Mousetrap Recap

Je Moon-jae had a difficult upbringing and lost his parents at a young age. Although the authorities believed it to be an accident, he knew that his mother had committed suicide by driving her car into the ocean and taking his father with her. In the aftermath, he developed a severe panic disorder requiring constant medication. Eventually, he went on to publish two highly successful novels, both under a pen name. Since then, he has been living in the secluded safety of his luxury apartment, living the life of a recluse with no real connections to the outside world. His only friend, Soo-hyun, who is also his accountant, remains his go-to solution for every problem. For the same reason, Moon-jae leaves him to fix things when the bank app on his phone begins to act up. Shortly afterward, his entire life turns upside down.

Moon-jae wakes to find that Soo-hyun, who handled all the paperwork for the apartment, has sold the place, which gets him kicked out of his house without any notice. However, things worsen when the author tries to track his friend down to their high school reunion. At the event, his former classmates refuse to believe that he is the real Moon-jae, as many of them claim that they have been in contact with him over the past few months. Likewise, at the police station, he fails to prove his identity since he has no identification on him, and unbeknownst to him, everything has been updated. Around the same time, local cop Park Sun-yong receives an anonymous tip connecting retired gangster Noja to the discovery of an unidentified dead body in the Han River. Previously, inaccurate database information had sent the detective to Moon-jae’s house in search of his suspect. The author had denied any connections to the man.

Therefore, it becomes a point of interest for Sun-yong when he discovers that Noja has recently been chasing Moon-jae. As it turns out, the author and Soo-hyun had previously stolen huge amounts of money from Noja through a book deal. Now, the latter has returned to collect. After an initial cat-and-mouse chase, the protagonist ends up willingly going to the former loan shark and makes him an offer. He wants the ex-gangster’s help in locating his doppleganger in order to prove his identity. In turn, he promises to return the money he owes and more. As such, the two end up forming an unlikely partnership. Their first lead, Soo-hyun, falls through when the accountant commits suicide. Later, the duo is blamed for the kidnapping of the deceased’s young daughter. All of this has been the plan of the real kidnapper, the elusive Rat, who got plastic surgery to become Moon-jae’s perfect lookalike.

Initially, Moon-jae comes up with a potential suspect behind the Rat. He thinks that the doppleganger could be Seo Yu-min, a writer he met in college who was extremely envious of him, especially because of his ex-girlfriend, Min-yeong. Nonetheless, when they follow the lead, they discover that the other man died two years ago. Simultaneously, the Rat gets ahead of Moon-jae by going to the police, as the author, and reporting identity fraud. With Soo-hyun gone, the protagonist has no legitimate way to prove his identity. As a result, even Noja’s confidence in the writer begins to dwindle. However, he has a definitive way to verify if his partner is truly who he claims to be. As it turns out, Moon-jae has an estranged uncle he didn’t know about, who can be his saving grace in this entire charade. Yet, once the Rat learns about the same, it sets off a race against the clock between the two.

Mousetrap Ending: Who is the Real Moon-jae?

The protagonist is introduced in the narrative as Je Moon-jae, who goes on to become a victim of severe identity theft. However, the motives of the doppleganger, aka the Rat, aren’t simply fueled by monetary greed. Instead, he seems to have a personal vendetta against the man. For the same reason, initially it seems obvious that the tormentor is the fake and his victim is the real Moon-jae. Yet, things take a turn near the end when the protagonist finds himself in police custody, sitting across the interrogation table from Sun-yong. During their conversation, he convinces the detective that Yu-min, whom he believes to have faked his death, is behind the entire charade. In turn, the officer believes him and helps him escape. Even so, he also takes a detour to verify the author’s story. The latter had claimed that Yu-min had faked being a college student when they first met.

This ends up being a vital piece of the puzzle. In reality, when Sun-yong checks the college records, they show that Yu-min had been a real student at the institution. This compels him to believe that the Moon-jae he met is lying and is actually a fake. Similarly, several other instances bring the protagonist’s legitimacy into question. For instance, the Rat’s manuscript matches the original novels so well that it even fools his longtime editor. On the other hand, several contradictory flashbacks to Moon-jae’s childhood suggest an internal conflict with his identity. Eventually, all of this is solved through a final confrontation between Moon-jae and the Rat aboard a ship suite on the ocean. As it turns out, although the protagonist is in fact who he claims to be, Je Moon-jae has been a work of theft and deception this entire time.

Before Je Moon-jae was born, his parents briefly adopted a child, whom they gave the same name. Later, once their biological son was born, the other kid was returned to the orphanage. However, this established a pattern where his parents were never satisfied with the Moon-jae that they had and constantly encouraged him to be a better version of himself. After the parents died, the son tried to give self-improvement a try by pretending to be a student at a college in order to join a writer’s club. There, he met Yu-min, a charismatic and gifted writer, who soon became the object of his envy. Moon-jae started hanging out with him and his girlfriend, Min-yeong, oblivious to their relationship. Eventually, the trio went on a trip together, where he learned about their romance. This became a catalyst in a violent altercation between the two boys. In the end, the protagonist, under drug influence, penned a steamy story about his friends’ relationship, pitching himself as the boyfriend.

After Moon-jae uploaded this story, both Yu-min and Min-yeong left the college. Meanwhile, the former deluded himself into believing that the story he had written held the real version of events. In his mind, he was the gifted writer and Yu-min the envious friend. Not only that, but Moon-jae also stole his friend’s journals containing full outlines of his novels. From these stolen ideas, he made his career, earning acclaim and accolades for work that was never his to begin with. As such, Moon-jae’s life as we’re introduced to it at the beginning of the show is, in fact, a stolen one. In his own inability to embrace who he was, he had stolen Yu-min’s identity in the most intimate of ways. Thus, when the latter turns around and does the same to the protagonist, it’s as much an act of reciprocation as it is retribution. In the end, the protagonist turns out to be the real Moon-jae. However, the person that he is has been a fake and an imposter all along.

Who Dies at the Ship? Moon-jae or Yu-min?

Alongside being the location for ground-shaking revelations, the ship also becomes the site of a final showdown between Moon-jaw and Yu-min. The latter has planned to send his nemesis on a wild goose chase to the beachside, where he plans for the cops to catch the author red-handed. Nonetheless, after days of experiencing his brand of torment, Moon-jae figures out his plan, tracks him down, and opts for a one-on-one showdown. After the initial violence, an appearance from the vessel’s staff becomes inevitable. However, this corners the duo into an impossible corner. Aboard the ship, there’s no place to run. Therefore, by the time they arrive on the next shore, both of them would be caught. Revealing Yu-min’s real scheme is out of the question for Moon-jae, who stands to lose everything from the discovery of his demented plagiarism.

However, if the Rat gets caught, the truth would inevitably come out anyway. As such, only one of the two can walk away from this encounter alive. In the aftermath, when the ship reaches harbor, where Sun-yong is waiting for Moon-jae with the authorities, only one man with Moon-jae’s face deboards. He’s dressed like Yu-min’s version of the author and occupies the same context. He claims that he had fought off his doppleganger after he attacked him on the ship. Ultimately, in his story, the latter fell off the suite’s window and into the ocean. Even though the author is pretending to be the version of Moon-jae we know to be the Rat, it’s actually the protagonist himself.

During the fight in the suite, Moon-jae managed to emerge victorious, defeating his doppleganger and ultimately pushing him out of the broken window. Yet, in the aftermath, he chooses to flip the script. He steps into the role of the composed author who has been in the limelight all this time. Inversely, he establishes that the person hanging around with Noja, whom the authorities suspected to be the imposter, actually died. This proves to be another installment in a long-established pattern of Moon-jae’s inclination to be a different, better version of himself, oftentimes at the cost of deception. He’s so ashamed of his cheating, plagiarism, and deceitful self that he would rather erase the last few days of his life and play out the narrative that Yu-min had constructed for himself.

Why Does Moon-jae Not Remember the Fire at His High School?

One of the earliest moments in which someone close to Moon-jae doubts his identity stems from his encounter with one of his former high school classmates. Before stealing the author’s life, Yu-min had established a pattern wherein he would visit shops near his victim’s apartment and grab lunches with his friends to establish alibis and connections that his reclusive counterpart won’t have. Therefore, once the switch happens, these people are more likely to believe the Rat is the real Moon-jae. However, the high school friend has a legitimate reason for his confidence. During high school, Moon-jae’s class witnessed a hotel fire during a trip. The Rat has talked of this pivotal incident from the author’s past. However, the protagonist himself has no memories of the event.

This is because of the same reason that Moon-jae has a distorted memory of his friendship and eventual fallout with Yu-min. When the protagonist was a kid, his mother used to advise him to be the best version of himself that he could be. After his parents’ death, he would often fail at this task. For the same reasons, he would end up rewriting these memories in his mind to preserve an idealized perception of his own self. The reason Moon-jae doesn’t remember the fire during his high school trip is that he was the one who started it in the first place. It was a small act of rebellion that allowed him to escape from the person that he thought he was meant to be. However, since it painted him in the worst light possible, he ended up willfully blocking that time of his life from his mind.

What is Yu-min’s Book the Rat About? Why Did yu-min Publish it?

During the events of the series, Moon-jae is engaged in an onslaught of adventures in a desperate attempt to prove his legitimacy. In the meantime, Yu-min pursues a different goal of his own. He continues surveilling his enemy and setting up game pieces to ensure everything plays out according to his plan. Simultaneously, he also works on publishing Moon-jae, the author’s third novel, The Rat. The book is released after his death and becomes a big hit, leaving the fans clamoring for the sequel. However, the real Moon-jae, who has no idea about the contents of the novel, ends up being the one who has to complete it. Once the author actually goes through the novel, he realizes that it’s about himself. Moon-jae has made his life and career by stealing Yu-min’s story and pitching himself as the protagonist.

Therefore, in a feat of fair commupence, the latter flips the tables and does the same to the other. The Rat, inspired by the folktale of a rodent becoming human by eating someone’s fingernails, tells the story of how Moon-jae buried his own reality and stole someone else’s life. The book is easily passed off as the work of the beloved author who penned titles like Interview and Evil Always Prevails, since the other two novels have always been Yu-min’s stolen work. Nonetheless, this time around, Moon-jae has no pilfered notes to plagiarise from. Moreover, he’s left to do the one thing he’s incapable of: self-actualize. Thus, in the end, the protagonist ends up losing his mind, unable to keep up with the web of his own deceit. Ultimately, his decision to once again reveal Yu-min’s identity, this time to preserve his own public image, ends up dooming him.