Episode 4 of Big Mouth picks back up from the ongoing fight between two groups — the man who tried stabbing Chang-ho and a few other inmates versus Chang-ho and his few supporters. As the psychopath attacks Chang-ho, the room leader steps in and takes the hit. The warden sees this and tells the guards to intervene.
Later, in the prison’s hospital wing, the warden asks the room leader why he chose Park Chang-ho’s side. The room leader whispers something in his ear.
All those involved in the fight are in solitary confinement. Soon, the cell doors are opened and Chang-ho, Jerry, and another inmate are let out, while the stabber and his two companions are not.
In the VIP room, the three men and the warden argue about who is to blame for the plan going wrong. The warden says if there is an investigation then they all will go down. They insist he not let Gong Ji-hoon find out about this and tell him to finish the job with Park Chang-ho.
At Gucheon University Hospital, Mi-ho gets in trouble for giving the wrong dose of medicine but realises she was given the wrong information on purpose. Someone seems to be trying to get her out of the hospital.
During a conference, Mi-ho makes a statement in front of everyone saying that she has Professor Seo’s unpublished paper. Later, someone follows her on her way home but she meets her father before anything happens. She then gets a call from Mayor Choi, who wants to ask her about the paper. They arrange to meet.
In the prison hospital, Chang-ho meets the room leader. The room leader asks him if he really is Big Mouse. After a moment’s hesitation, Chang-ho says that he is.
The man who tried stabbing Chang-ho is found hanging in his cell. The warden asks Chang-ho if he did it, saying it’s very convenient that the man who tried to kill him is now dead.
The mayor meets with Mi-ho. She reveals that she is trying to find the paper and needs his help. When he asks why he should help her, she says he is the reason her husband is in this mess. The mayor replies that con artists scam the ones closest to them first. Mi-ho stands her ground and tells him about the do-not-resuscitate orders at the hospital. She suggests his wife knows more than she is saying, but the mayor trusts his wife.
After the inmate’s suicide, the other prisoners fear and respect Chang-ho a little more. As Chang-ho does pull-ups sitting on another inmate’s shoulders, we hear a voiceover describing it.
Gong Ji-hoon then visits Chang-ho in prison. He tells Chang-ho to return Lala Capital’s 100 billion won. Chang-ho claims that if he does so, Ji-hoon won’t have a reason to keep him alive. Ji-hoon doubts his identity and tells him to name five clients of Big Mouse. He gives him five days to come up with the names. After the visit, Chang-ho knocks his guard unconscious and uses his phone to call the mayor. He tells the mayor everything and asks for his help in getting the names.
The mayor gets his people to spy on the prosecutor (who got him the list of drug dealers in the first place) and Gong Ji-hoon.
Meanwhile, the remaining two inmates in solitary confinement get increasingly scared and anxious that Big Mouse is going to get them. The warden orders them to be sent to the general ward.
Later, the two inmates enter the cafeteria. They begin to eat but suddenly collapse. Both of them froth at the mouth and die. Chang-ho realises the real Big Mouse must be close by.
The warden and some detectives watch the cafeteria CCTV footage and find that both inmates ate cyanide themselves.
The guards search Chang-ho’s cell thoroughly but don’t find anything. The warden tells the other watching inmates to stop enjoying the show, but they don’t move. Chang-ho takes a step ahead and gives them one withering glance — which has all of the prisoners retreating to their cells. The warden calls his bluff and warns him, he has four days left.
Gong Ji-hoon arrives at a stately house to meet someone who is referred to as the Elder. Joo-hee is also there and has just met with him. The Elder refuses to see Ji-hoon until he has got the 100 billion won back. Instead, Ji-hoon is instructed to go offer Mayor Choi support at a dinner with some influential politicians.
Ji-hoon arrives at the dinner and talks up Mayor Choi but later in the restroom, the two men argue. Ji-hoon takes credit for making Choi Do-Ha mayor but in turn is accused for using the mayor’s position for his personal benefit. The mayor leaves and Ji-hoon makes a remark insinuating that he has something up his sleeve that could ruin the mayor’s life.
On the way home, Mi-ho notices someone following her for sure this time. She, her father and Soon-tae make a plan and capture the man — who turns out to be the mayor’s secretary. They call the mayor and ask him to explain himself. The mayor arrives and says he did it for her safety. He then hands over a piece of paper with some names written on it and tells Mi-ho to give it to her husband.
Mi-ho visits Chang-ho in prison and gives him the paper. Thankful, Chang-ho calls the mayor and asks what made him change his mind. The mayor says that if Chang-ho really was Big Mouse, then he wouldn’t have asked. Mi-ho asks if Mayor Choi can be trusted.
While drinking together, the prosecutor and Ji-hoon discuss how the list of drug dealers given to the mayor was fake. The two are really in cahoots! Turns out, Ji-hoon made up the names and wants to see where the mayor will use them. He thinks those words will come from Chang-ho’s mouth.
Rumours abound in the prison about Big Mouse’s capabilities. Someone also seems to be taking bets. Bags full of transportation cards enter the prison, each with a limit of 100 million won. The question seems to be who will last till the end of the month, Big Mouse or the three VIPs.
Jerry is revealed to be running the bets. The three VIPs have him beat up and taken to Chang-ho. They argue and make a bet on whether Chang-ho knows the drug dealer’s names or not.
At an art gallery, the mayor is looking at a painting when Ji-hoon comes up to him. He is on his way to meet Chang-ho and asks the mayor if he wants to join. He then reveals the list the mayor has is fake. Panicked, the mayor tries to call the warden but he intentionally doesn’t pick up.
Chang-ho steps out of his cell to go meet Ji-hoon. The surrounding inmates are watching. They start stomping on the ground and chanting ‘Big! Big!’. Chang-ho proceeds to meet Ji-hoon.
The Episode Review
The pace is picking up and it’s about time. As Chang-ho settles more and more into the role of Big Mouse, it’s thrilling to see him faced with a deadline to prove himself. Things at the hospital are intriguing but moving a little slowly.
This episode comes with some exhilarating moments, particularly the scene where the inmates don’t heed the warden’s warning but retreat with just a glance from Chang-ho. Goosebumps!
The big reveal that the prosecutor and Ji-hoon are working together and that the list of drug dealers was a fake, is also a nice twist in the story. It leaves us at another tense end-of-episode cliffhanger, a trend which is exciting and keeps one waiting for the next chapter on tenterhooks!