Episode 4 of Mouse begins with Bong-Yi’s grandmother trying to get away from the killer. It’s no good. Our killer stabs her, leaving the woman for dead and walking away. Tellingly, he doesn’t deliver the killing blow but lets her bleed out instead.
Meanwhile, Mu-Chi hears from the Captain. He and Ki-Hyeok race off to another crime scene but on the way, Bong-Yi happens to be waiting by the end of the bridge, prompting the duo to give her a lift.
After dropping her off, the team make it to the scene where they find Bong-Yi’s grandmother is dead. Mu-Chi is distraught and heads outside where he finds Bong-Yi standing, shocked at what’s happened. He tells her not to go inside, but it’s too late. Bong-Yi’s grandmother is taken outside on a stretcher, prompting Mu-Chi to reluctantly let Bong-Yi identify her body.
At the hospital, Ba-Reum gives his statement to Mu-Chi. He gives crucial clues to go on, including how the killer was left handed and smelled of mint. This seems to hint further toward Yo-Han being the one responsible. Before he can probe further though, police officers arrive and tell him to stop.
It’s been 2 months since these killings began and the police are still no closer to solving this. Even worse, with no dashcam footage and no CCTV in the area either, all Mu-Chi has to go on is Ba-Reum’s statement. And eye witness accounts are not accurate.
Thankfully there is one camera that may have picked them up. When Mu-Chi shows, the pair start going door to door, asking if anyone has seen Bong-Yi’s grandmother in the area. Unfortunately the cleaning lady decides to keep quiet, especially given their boss has been hiring illegal immigrants.
The investigation tightens up, with Mu-Chi bringing three teams into the fold. While they begin cycling through the CCTV, Bong-Yi mourns the death of her Grandmother. She’s distraught, blaming herself for the last things she said to her grandmother. With Ba-Reum by her side though, she’s hopeful she can get through this.
Meanwhile, Mu-Chi receives word from the CCTV team. They’ve caught a glimpse of Bong-Yi’s grandmother, sending the team off to investigate the area around Yo-Han’s house. Eventually though Mu-Chi decides to turn his attention to Yo-Han, believing he’s a shady character and a possible culprit.
Before he can do so, Mu-Chi receives a call from the boss, telling him to head back to the office. The whole country is waiting for his statement, and thanks to being the murderer’s target he’s forced to stay at the station for the time being. He has a statement to write out after all, but instead he decides to fall asleep.
While this is going on, another child goes missing, this time from an amusement park. This seems to link to Professor Lee’s death but it’s unknown at this point whether it’s connected or not.
Mu-Chi gives his statement on TV but midway through the live broadcast, receives a call from the killer. He taunts Mu-Chi, telling him to figure out why he chose the kid and to sober up and take things seriously.
He claims to have a very methodical, specific way of picking out his victims. If Mu-Chi can figure that out, it could save the child’s life. This time though, the killer is demanding a ransom. If they don’t pay up by 11pm on Friday, then Han-Kook will die.
Using an old case called BTK as an example, Mu-Chi decides to take the stage and conduct a theatrical investigation to figure out who’s to blame. With only 4 days to get to the bottom of this, another twist in the tale is unveiled when Mu-Chi’s phone call with the killer is leaked to the media. This makes him the center of attention.
As Mu-Chi heads back into the police station, he runs into Doo-Suk who happens to be waiting for him. He warns Mu-Chi over this killer and tells him not to take things lightly. Well, this and the public outrage prompt the authorities to make their move, deciding to cancel the show.
Unable to take this, Mu-Chi hands in his resignation in frustration. Only, Han-Kook’s Mother arrives and gives an impassioned cry, pleading with him to keep fighting and finding out the truth. This is enough for Mu-Chi to continue on as he starts sifting through the different clues he has to work with. It also turns out the item wedged in one of the victims’ throats was an insect.
With all these different victims coming from very different walks of life, the group are torn and unsure exactly how all of this fits together. Well, for now Mu-Chi heads on-air and does his show as another victim shows up. This man seems to have been dead for several days, leading the detective on scene to notice his watch. It’s pointing at 8.10pm on the 28th of the month. The TV is also on the same channel Mu-Chi is starring on.
On TV, Mu-Chi taunts the killer, telling them to phone and reveal why they’ve taken Han-Kook. As Yo-Han gets up and heads down to the basement, the scene suddenly changes as we see Ba-Reum enter, where he’s the one who’s kept Han-Kook captive. Oh no…
So it seems like we’ve got two killers on the run, with Yo-Han serving as a red herring of sorts. It’s fair to say Jae-Hoon has probably grown up to become Ba-Reum, which backs up the story about his family being deceased when he was talking to Bong-Yi a few episodes ago.
However, despite his big shock reveal there must be another psychopath (or two) on the hunt as well. The middle finger/church crimes seem to be very deliberate and emotionally driven – probably from someone who doesn’t like God or has been wronged by him in the past.
This fits the narrative with it being Yo-Han (cursing God for being the son of a psychopath, a path he himself has taken) or it could even be Mu-Won too.
At the same time, we’ve got Chi-Kook, who’s the only survivor of this – and with his finger found at the crime scene. This is the one that’s most baffling because it seems the most amateurish and sloppy. Could it be that our killer has a protégé that’s learning from him and beginning a serial killer spree?
Either way, the reveal that Ba-Reum is the killer is not only a shocking way to end this episode, it actually makes a lot more sense with the evidence we’ve seen so far. This is shaping up to be one heck of a thrill ride and with lots more episodes to go, Mouse leaves the door wide open for next week’s double bill.