Ha-Na interviewing a serial killer called Chul-Young. He expresses no regrets over killing his previous victims, chillingly claiming he's been forgiven by God for carrying out these acts.
Ha-Na is irate and leaves the prison, calling him a lunatic. This seems to fuel her, as we cut back to the present again. Ha-Na watches Do-Ki with the Deluxe Taxi, snapping photos of him arriving into a garage.
With this lead, Ha-Na ferociously pursues the case, looking into the history of the taxi agency and all of its workers. Everyone is meticulously pored over, including Jin-Eon and Go-Eun.
Ha-Na immediately heads to the Director and shows him an arrest warrant for Sang-Chool. She's done her homework and has all the evidence needed to assign the same taxi from the tunnel to that of the one Do-Ki drove to his house the previous night.
After promising to do what he says if she fails to find evidence, Ha-Na is given the green-light to pursue this lead. While Ha-Na is busy, the Director immediately heads to Sang-Chool and mentions the serial missing person's case. He divulges details about the taxi and what transpired, eventually admitting that they've got a search warrant for his place.
The group are forced to hide out in the basement, switching all the lights off and hoping that they can evade the authorities long enough to survive this.
Survive they do; no evidence from Sang-Chool's is found and all our Blue Bird employees come out unscathed. It's incredibly lucky, especially given Ha-Na was moments away from finding the basement hidden behind the picture frame.
With the search a bust, Ha-Na confronts Do-Ki out in the street later that evening. She asks him about Doo-Chul, prompting the pair to verbally spar over their differing ideals. While Ha-Na abides by the law, Do-Ki questions just what the law has actually done to help them. The conversation ends with Ha-Na hitting a nerve, bringing up Do-Ki's unbridled anger.
When Sang-Chool returns to the prosecution office, the situation is cleared up (for now) and he's given a new case for Blue Bird to deal with. This involves a church, with Sang-Chool and Ha-Na's team both working parallel to one another on this case.
Pastor Ko is the victim and when Ha-Na arrives to see him, he's already been picked up by Do-Ki. His son, Dong-Hee, went missing. Chairman Baek's right-hand man Secretary Goo is the culprit. He drugged the man's drink and took him back to his office. There was one other witness, a man by the name of Sim Woo-Sub.
Both men left while Dong-Hee was still inside. With no way out, it's unknown quite what happened to the boy – and if he's even still alive. All of this stems from a petty act of revenge over a girl called Hye-Yeon.
Speaking of revenge, Pastor Ko is given the choice between gaining revenge or leaving things as they are. Relying on faith, he punches the blue button on the arcade machine. He doesn't want to resort to this act and claims Dong-Hee is still alive.
Back at Blue Bird, the team's work is done and they decide to simply send the money across to the foundation. However, Do-Ki is not ready to give up just yet.
Ha0Na takes charge of the situation, using legal means to find out what happened. Dong-Hee was brought to an apartment where blood spatters confirm he was beaten. Unfortunately a lack of conclusive evidence means Goo is not behind bars for long and he eventually returns to business as usual.
The pendulum swings back Do-Ki's way again, as he watches from afar as Goo brings Woo-Sub inside and begins threatening him. While Do-ki watches from the window, he's taken aback when Goo is standing byy his side. It seems there's two of them and they're both identical twins
Well, Chairman Baek gathers everyone together, including Do-Ki and Sang-Chool. She reminds them both that they stay behind the lines. As the conversation ends with an uneasy tension, Woo-Sub is brought in by the police for questioning. He eventually decides to betray Secretary Goo, especially after his earlier altercation with the man.
Well, this entire operation includes Woo-Sub convincing Goo to reveal everything about what happened with Dong-Hee. They both go out for drinks and WooSub does his best to loosen Goo's lips. Ha-Na sits at her desk and listens. Goo whispers exactly what he's done in the man's ear, prompting Woo-Sub to wait for the man to pass out before calling him a fat pig and leaving.
Unfortunately his phone call to Ha-Na is intercepted by the two brothers both working together. "Save me!" He blurts out before being thrown through a window to the ground below. Mr Sim survives though, but it sends Ha-Na and Mr Wang both out to track him down and save the man from his fate. However, Do-Ki gets there first and the two fight. That is, until police show up.
The officers are pretty useless in truth, especially given Mr Sim is stopped by Goo, who smashes him in the leg with a steel pipe. Unfortunately everything ends with devastation as Mr Wang is found dead and the twins manage to evade capture. Ha-Na is distraught.