Episode 2 of Mouse begins at Guryeong Police station as Jae-Hoon leaves out the front door and looks up at the sky. He bemoans God Almighty not listening to his cries, as we see a snapshot of his grizzly murders through time.
We then cut across to Mu-Chi, who’s older now and chasing an assailant across the rooftop. The voice in his head pleads with him not to kill, as he stalks a man up to the very edge of the building.
After taunting and threatening to shoot, the man jumps to his doom. Mu-Chi simply sits and thinks, drinking heavily. In his drunken state, Mu-Chi shows up at a crime scene and gives an interview to the reporters on scene. One of the people watching though happens to be our killer, who certainly perks up when he hears Mu-Chi talk.
Later that day, Mu-Chi visits Han Seo-Joon in prison. The two trade verbal blows, as Seo-Joon tells him he’s unable to kill anyone – he can tell by looking in the boy’s eyes.
Well, it seems like these meetings have been frequent, with Mu-Chi telling him the only retribution is in delivering an ‘eye for an eye’ punishment. In this case, killing Seo-Joon’s child. Despite his best intentions to hide this fact, Mu-Chi has seen them himself and promises retribution.
Bringing Seo-joon back to his cell is a new prison guard called Chi-Kook. He promises Seo-Joon that his time of being comfortable is at an end before locking him up. He meets his friends after work, telling them he’s doing his best not to let the inmates intimidate him. However, that’s easier said than done with characters like the Head Hunter there.
While helping Jung Ba-Reum move some heavy items the next day, Chi-Kook points out the Head Hunter in the yard who sits reading a book. As we cut across the yard, it turns out he’s rallying the inmates to take out the prison guard.
Well, later that evening a magic show goes horribly wrong in the assembly hall. Chi-Kook is found bleeding out and close to dying. Seo-Joon offers his expertise and eventually they all agree to let him work his magic (no pun intended) to save the boy’s life.
After stitching him up, they take him to the hospital where the doctors comment that two fingers are missing. However, they do manage to find those at the crime scene and rush them into surgery.
Chi-Kook pulls through where it turns out Seo-Joon’s subordinate was the one responsible for what happened. For now, the officers are checking to see if there’s any connection but it certainly looks that way.
Meanwhile, Mu-Chi notices footprints at the crime scene and heads back to the station to investigate. There, he finds that the officers already have a suspect and an eye-witness. Mu-Chi tells them they have the wrong guy, pointing out the shoe size as a factor.
Tagging along for the ride is Choi Hong-Ju, who happens to be a reporter working on TV. He tells her to leave but unfortunately she has leverage over him in the form of incriminating pictures showing him gambling. On the back of this, Mu-Chi is forced to allow her to tag along.
Together, they arrive at the crime scene and re-enact the position of the body. With a middle finger brandished, they realize it points in the direction of the church across the road.
Next, they visit the boxing ring where the burnt corpse was found, and once again the open window points toward the church. With items taken from both crime scenes by the killer, Mu-Chi deduces that this can only be the work of a psychopath.
After a trying day, Choi Hong-Ju starts editing together her show. Eventually she broadcasts it, where our mystery psychopath happens to be watching from home. As he clenches his fist, we cut to another crime scene.
This one takes place as a construction site where a homeless man in his 50’s is found. The police estimate the man had been dead for 15 days prior but this is just the beginning. As we hear the serial killer’s thoughts, he decides to pick an easy target next, which includes a dead cat found nearby.
When Ba-Reum and the other officers arrive, Ba-Reum winds up vomiting after seeing this the cat. After, he begins putting up posters, warning over the serial killer on the loose.
After listening to her grandmother gush over Officer Jung, Oh Bong-Yi leaves her house and runs into Ba-Reum. He warns her over the killer and encourages the girl to take some medicine for the cut on her hand. Bong-Yi is embarrassed though and eventually walks away.
While she does, Ba-Reum runs into her grandmother and notices she has a pretty swollen ankle. He encourages her to stay home and not put weight on her leg, suggesting instead that he be the one to pick up Bong-Yi when it rains.
Bong-Yi meanwhile, runs into Mu-Won. We’ve seen him in fragments across this episode and he’s very much found solitude in God. The two talk together about the Lord and how he’s forgiving but Bong-Yi hides a dark secret. Something happened to her puppy in the past. Even worse, she was taunted by the killer as a child, promising that he’ll see her again soon.
Mu-Chi is called to the scene of another crime, this time with a woman hung by a noose. She’s wearing all the collected items from the different victims but also happens to have a watch that’s not been found on another victim. With no church or cross in sight, Mu-Chi examines the body and once again finds the middle finger…pointing inside her mouth.
Upon removing it, he sees a cross etched on the roof of her mouth. On top of that, there’s a message on the ceiling scrawled in blood, taunting him. The killer congratulates Mu-Chi for a job well done and claims this was a gift.
After visiting his Father, Seo-Joon, in prison, Sung Yo-Han begins to leave the police station but spies Ba-Reum from across the main atrium. As they stare one another down, the episode comes to a close.
Following a time jumping opener, Mouse starts to settle down and build up the ensemble of characters we’ll be following across the season to come. The interesting fortunes for our two brothers, Mu-Chi and Mu-Won, is a nice touch and it’s backed up by the wild card of Ba-Reum who may well be holding secrets of his own about his past.
Meanwhile, it seems like Sung Yo-Han may be the one responsible for this new string of murders but it could also be a red herring too. After all, it seems a little too obvious that the son of a serial killer is the one now committing all these murders. Could it be that Ba-Reum is actually the son of a serial killer too? Could he be a twin brother?
Either way though, it’s interesting to see this cat and mouse game play out with Mu-Chi trying to track down this new serial killer. There’s been a lot of emphasis on his drinking and hauntings from the past too, while Ba-Reum has been shown doing good deeds and helping as much as possible. Could this be a big factor going forward?
There’s certainly a lot of possibilities here though and this second episode keeps the mystery and intensity pretty high throughout its run-time.