“Mouse” Heartbreaking Ending Explained- Episode 20 Recap And Review

Published Categorized as Kdrama Recaps

tvN’s “Mouse” has ended its run last night, and as expected, the ending was both heartbreaking and necessary.

Today, I am here to quickly recap “Mouse” episode 20, and discuss my thoughts on the drama’s ending.

Below is a recap of “Mouse” episode 20 highlights, it is not a detailed recap

Note: this will be a spoiler review of the said episodes in the title. This is a subjective review.

Table of Contents:

  1. “Mouse” episode 20 recap
  2. Mouse final scene-after credits
  3. “Mouse” Ending- Final Comments
  4. “Mouse” final thoughts- review

“Mouse” episode 20 recap


Ba Reun confronts Councilwoman/Mrs. Choi and she admits she’s orchestrated the entire ordeal. When the bill to abort children that have psychopath genes was rejected, it gave her the chance to put on a secretive operation to prove to everyone why its needed, Yo Han disappointed her but Ba Reum didn’t.

She convinced Dr. Daniel to give her the list of kids who have the psychopath gene and monitored the two families.

This is also why she ordered Song Soo Ho to kill his mother who tried to kill him and the rest of his family. She says it was a mistake and the incident tormented that man but it was necessary for the experiment to succeed.


She did all of that to prove her point and be able to create world without murder and issues by eliminating psychopaths before they’re even born. As a result, Ba Reum tries to shoot her with a gun and she’s okay with it because it means what she said was right and killing her will be the ultimate proof that people like him shouldn’t be allowed to be born.

He doesn’t kill her eventually, and Moo Chi finds the place, he rushes to it and arrests her and escorts Dr. Daniel. He also retrieves evidence from her house.

Turns out, Ba Reum also had Bong Yi locked up and his aunt came for her, she finds out through the aunt and rushes to confront him.


Meanwhile, Moo Chi is still searching for him and has a police officer trace Bong Yi’s phone. He gets a phone call that confirms Ba Reum killed his brother.

Bong Yi attempts to kill Ba Reum who fights her off at first because he doesn’t want her to end up a murderer. But eventually as he’s about to cave in, she realizes she can’t kill him.


Moo Chi arrives at the scene and points a gun at Ba Reum who is begging to be arrested. He swears at him and shoots the gun. But from behind, the PD hits him on the head rendering him unconscious.

Moo Chi wakes up the next day in the same location and finds out Ba Reum was arrested and admitted to being a serial killer.

As he’s arrested, the PD is standing there recalling the time she went back to the abandoned place and found Dr. Lee who tells her if it weren’t for Yo Han he’d be dead, that’s also when she found out it was Ba Reum.


The PD and Dr. Lee band together to clear Yo Han’s name. The PD will take care of the doctor on the condition he uses him to kill off a couple of psychopaths before his instincts awaken.

At the police station, Yo Han’s mom shows up to see Ba Reum. Turns out, she’s Ba Reum’s mother and had agreed with Yo Han mother to switch babies. One day, she went and saw Ba Reum attempt to bury his little brother, so she tried to strangle him. She didn’t do it eventually and told his mother about it.


So, she sought after him to kill him then herself but his aunt came and took him away.

When she saw in the news that someone was killing people, she knew it was her son so she sought out after him again but Yo Han had tried to get to him. At the hospital [back then], she came to his room and he regained his conscious. She came after him to his house and saw that he could’ve really changed.

As he’s moved away by police, he tells his mom he didn’t kill his family or his little brother.

Yo Han’s mother then confronts Moo Chi at the hospital and tells him her son didn’t die because of him but because Han Seo Joon killed him so he shouldn’t feel guilty.


Ba Reum confesses to police that Han Seo Joon had a hideout and he’d planted Yo Han’s brain into him despite Yo Han having been alive and well.

Moo Chi then confronts Han Seo Joon who confesses he’s done that, Moo Chi tells him he was being toyed around by Ms. Choi.

Flashback to the day Yo Han confronted his mom- before he was murdered

Yo Han sees a photo where his mom is holding another baby, he confronts her and she collapses and apologizes. He says he won’t forgive her, or her son for killing his family and that he will kill Ba Reum himself.


As she recalls those events, Yo Han’s mother commits suicide.

At the police station

The arrest warrant for the councilwoman will get rejected because the elections are near. Then to help them out, Ba Reum’s aunt tells the press she’s part of the secret organization that ran this experiment and says she’ll hold a press conference. However, she doesn’t show up.

Ba Reum suspects she was taken away so he tells Moo Chi to find her. He focuses his efforts on finding her and sees that she was taken away by Min Soo. Meanwhile, the PD meets Bong Yi and asks her for help, she presents her the evidence they have and says she needs her.


Turns out, the councilwoman also can’t find the man who took away the aunt. Luckily, he hid them away and Moo Chi comes finding them.

At the interrogation room


Ba Reum says he killed his first man as he was looking for him because he killed his family and after that, the monster inside him awoke.

At the TV station


The PD is airing a live broadcast to expose the organization behind the experiment on Ba Reum and Yo Han. She brings testimony from Dr. Daniel and the aunt herself who exposes Mrs. Choi on live TV as she’s exiting the police station after they failed to issue an arrest warrant.

Video footage shows Mrs. Choi ordering people around in regards to the experiment. She is arrested as she departs the station.

At the TV station

the PD admits she’s also involved with the case, she’s killed a woman 26 years ago and made a plan with Dr. Daniel to make Ba Reum kill the psychopaths.

Outside the TV station, the police show up to arrest her, her father goes up to her to handcuff her and asks her why she took so long, she cries and says she didn’t think she deserved happiness.


Thus, the rest of the organization personals get arrested and trialed. The new president gives people the chance to choose whether they want to pass a law that says psychopaths should be aborted.

Ba Reum pleads guilty to all charges and is sentenced to death. He cancels his appeal as well.

6 months later

Ba Reum is escorted to the same prison where his dad is.

At the prison, he has a confrontation with his friend who is now a guard. Ba Reum nearly strangles him but other guards interfere. Ba Reum is then given the chance to visit the same cell as his father.

Turns out, Ba Reum asked his friend to allow him to go inside his father’s cell and open it for him so he could kill him.


After having a conversation with his dad, he proceeds to stab him multiple times killing him.

Later, people find out Ba Reum is dying and doesn’t have much time left. He’s in terrible pain.

Moo chi decides to visit him in jail, Ba Reum apologizes and asks him to use his assets to help out the victim’s families. He also asks him if he could bring Bong Yi so he could see her one last time.


Bong Yi agrees reluctantly and is harsh with words when she sees him. He apologizes to her.


At the church


Ba Reum is hallucinating, he sees his younger self and tells him the lord granted their wishes, they’re no longer a monster. He holds him and cries. Ba Reum dies.

3 years later

Mrs. Choi was granted pardon and gets out of jail. The PD also gets out of jail.


However, the man who escorts Mrs. Choi then takes her to a hidden place and takes out a knife.


Moo Chi now sells eggs to help pay for Bong Yi tuition for college.

Moo Chi later runs into the PD and they both apologize to each other. Both wish each other would live their lives to the fullest.


Moo Chi then goes to a place where he keeps a sort of grave for Ba Reum that says ‘rip.’

The end.

Mouse final scene-after credits


A doctor appears to be operating on two people transferring a part of their brains between each other, the final scene shows a young man who is being operated on.


The end.

“Mouse” Ending- so this is it?


So…. This is it? I mean, we’ve waited 20 episodes and this is the explanation for the entire ordeal? It doesn’t make any sense… I am just… I am astonished at how dumb the reasoning is.

So Mrs. Choi motivation was to make a ‘superior’ human race or a utopia and to eliminate crime? The only issue with that entire motivation arc is that it doesn’t make an ounce of sense.. nothing. Nada…

Even if we suspend our beliefs and assume every single psychopath will grow up to be a murderer, that is still a tiny portion of the population, added to that, it is not only that psychopaths commit crimes but average every day people do as well.

I can’t believe this has to be explained. There are a lot of crimes of all kind that happen because someone is too passionate or too emotional, relegating all the crimes to the world on the shoulders of psychopaths is shortsighted at best. Even if she correctly eliminates every psychopath, there will still be crimes, plenty of them.

Just because the drama operates under the ‘fiction’ category doesn’t mean nothing else has to make sense. This is basic human knowledge, this is not science.

Also, as a scientist, I find it very odd how she only thought of conducting experiment on two people only when anyone with a science degree can tell you you need more than that to establish a connection between the arguments they present. Forget the exorbitant expenses such a project entails, Mrs. Choi still has to explain how she directly influenced the death of many people to prove her argument thus, disproving that only psychopaths are capable of doing terrible things, look at what she’s done? How is she any different? For her to believe that with all her heart that eliminating psychopaths is the way to a happy living doesn’t resemble the way a normal human with a functioning brain works. That’s the issue.

I stand by my previous judgment, the drama didn’t need to be this long and didn’t need to be fiction. That entire plot-line of the ‘operation’ and the government involvement was too grandeur to be executed properly within the time frame they had to work with.

I don’t understand why they were so afraid of just making Ba Reum terrible and that’s it.

My solution would’ve been to say Yo Han died of natural causes, Ba Reum woke up with amnesia and because everyone told him he was ‘kind,’ he was convinced he was normal and thus slowly unravels how terrible he actually is.

That would’ve still been a solid plot development and a great use of the overly used trope of amnesia in kdramaland, but no, we had to settle for stuff that not only fail to make sense but also made the drama what it became to be.

“Mouse” ending- episode 20 review


Its been a long ride, a long one indeed.

It must’ve took one hell of a challenge to complete this project. Choi Ran has really outdone herself this time. I can only imagine how stressful it must’ve been for her. I appreciate how much effort must’ve been into every aspect of it.

My issue with the drama remains the execution. The idea is very interesting but the presentation needed way more work. You can tell the production was overwhelmed at many instances during the production. They wanted to tease viewers but were also terrified no one would pay enough attention to get it, thus, they’ve created multiple ‘special’ episodes that basically shout exposition in your face.

Exposition is fine and all but this drama suffers from an overload of it. Up until the very last moment, it is used extensively. I haven’t seen such a thing happen before. I am baffled to this day.

I really believe the drama would’ve turned out much better had it been pre-produced. This type of content and especially this type of drama needed to be written completely ahead of time. If that had been done, the project would’ve gone down in history as a legend and something so special, not that it isn’t but the execution remains weak.

I know many of you are very attached to this drama and won’t accept my thoughts on it, but these are my observations. I love murder content as much as your creepiest friend does but even this one was not easy to follow and felt frustrating at times.

I can tell the screenwriter had all the basic ideas in her head, which is great news because it helped the drama not become an illogical mess.

The drama also didn’t need to be 20 episodes long, 14 would’ve been more than enough for such a topic. They would’ve condensed so much and be able to keep people on their toes even more. I also disliked the editing in this drama, it was so darn frustrating. Characters would do something then another flashback happens that shows why they made a decision 10 minutes before. This pattern is repeated way too many times. I get it’s done to keep you on the edge but please, was it necessary for you to use it like 7 times in the last episode alone?

“Mouse” could’ve either been a fun stressful experience or almost a chore depending on your taste and tolerance.

Regardless, thank you to everyone who has worked hard on the drama, to the actors, the staff and the production.

So what did you guys think of “Mouse” episode 20? did you like its ending? Let us discuss in the comment section below!

Whats your reaction to this article?

By Jass K.

Hi, I am Jass k. I discuss some of the hottest currently airing kdramas on this site in form of reviews an/or recaps, join me in the discussion~


  1. I think you forgot to mention at the end of credits, there’s this scene of another brain transplant of two persons. Who do you think this person is?

  2. The story was too long and i think making Ba reum the serial killer and psychopath was a very bad idea cos been a hero suits him better than being a villian and would make viewers lose interest in the drama

    1. That’s why imho it’s stretched into 20 episodes with goverment polotical drama to ease the bad image of seung gi.

      @jkahoyy what if daniel lee who operates it. He pleaded to the 5th even though he didnt had any string attached to govt. As fellow scientist and han seo joon friend, he perhaps was intrigued by the brain implant result

  3. The over all purpose of the story centers a psycopath. Thats where the experiment came in. Crimes engaged by other normal person is given but what the writer trying to convey is what can a psycopathic character do alone. This is base from a true event happened in Incheon elementary shcool in 2017 which murder had been done by a female drop out student with an accomplice. Chopping and disposing the body of the 8yr old victim.
    20eps or 14eps, it is doesnt matter,as long as the viewers passionately watching the drama and able to related the story.
    For me,i enjoyed every bit of the scene.

  4. I’m still wondering who that person is… I personally think this drama was epic. Not something that we have seen in the kdrama industry before. I liked how they made a spin off in order to explain every bit of the drama without any loose ends..

  5. I believe the dragging part was necessary to cover all the mystery their was. I feel that this drama is likened to that of Shutter Island. You’ve got to watch it again.
    Yes it was a bit of an exaggeration but the inspiration was on a real serial killer case. And since in Korea, there’s not much of isolated killings unlike other countries. If there are, mostly done by psychopaths.. There were cases of serial killings in Korean history if you’ve done a research.

  6. Actually I think the idea of making utopia by eliminating psychopaths are very much based on real life. There are literally hundreds of fictional stories out there on how the world will become a better if someone just killed Hitler back when he was a baby, or Stalin, or *insert someone’s name here*. There are also efforts on detecting babies with possible defective genes and then abort then under the belief that living with defective genes will make them suffer in life. So yeah, it’s actually very realistic for humans to start playing God when they have the chance to do so.

    And psychopaths, whether they are actual predators or not, do carry with them the very literal possibility of threat to society. In the episode we saw that the society ending up voting for the choice to force abort any babies with detected psychopath gene. I’m pretty sure society will make the same choice if they are presented by the same option in real life as well.

    Of course, like you said, they can always make Yohan dead under normal circumstances and make the story focus on Bareum coping with his amnesia and newfound ’emotion’, but in that case we won’t even need Daniel Lee, or even Han Seojun. The story can focus fully on the emotional aspect of a ‘repenting’ psychopath, but then episode 1 will be completely irrelevant. Therefore I personally think OZ organisation is completely necessary as a plot device because of the premise set up in episode 1.

    Lastly, on the topic of another brain surgery, Han Seojun literally pulled off a successful frontal lobe transplant on humans, when in real life the successful operations are only on mouses. Once the fact gets out, of course many ‘unscrupulous’ doctors will try to replicate such a feat, either in the name of ‘medicine revolution’, greed, et cetera.

  7. I do agree with you that it felt draggy and threr are too many unnecessary repetitive scenes. Some of the repeated scenes did’nt even make sense because it was as if the POV is changed from one to another. Nevertheless, I still enjoyed the show. I liked how it’s able to potray a person without empathy turn into someone who has. I can vivily imagine how difficult it is for Jang Ba Reum to accept that he is the killer. It makes me think how serial killers will never feel the guilt and pain that the victims feel so it is pointless for victims to hang on the the anger for the sake of their own life. I cried buckets watching the last episode and even with its flaws, I fell in love it.

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