Back in where we see a small boy called Hyun-Soo watching the news, seeing the terrorist attacks on the twin towers. His Father happens to be Chul-Young, who's a serial killer. He viciously murders his victim while saying goodnight to Hyun-Soo. This then cuts us back to the present, as a mail addressed from Chul-Young ends up in the police station.
The Baek attacks last episode have certainly taken their toll on our characters though, as we jump back to the present. Sung-Chul has obviously lost his sight in one eye while Kyung-Koo has lost a finger. When Go-Eun sees this, she starts crying. However, Do-Ki does manage to wake up from his ordeal.
Back at the station, the Goo brothers bicker and give conflicting statements. Regardless, Ha-Na decides to convict them jointly. The statements that follow from the General Manager of UData point more evidence at Do-Ki, telling her he's to blame for his horrific ordeal. Ms Choi's statement only further compounds her concerns, especially when Ha-Na mentions the word jail. The woman drops to the ground and begs for forgiveness.
Sung-Chul gathers the troops together and believes they should admit the truth about their roles in the Rainbow Taxi Revenge Scheme. However, they receive word from the hospital first. Jin-Eon is still alive! He made it out after all and he's currently recovering in hospital.
To try and close things out, Do-Ki brings Ha-Na to Sung-Mi's hideout and shows her the prison cells. He accepts the consequences of his actions and pleads with her to make sure his colleagues don' get incriminated. Well, given what she's seen, and the shocking effect it's had on the prisoners, she's going to investigate this properly, promising to be in touch shortly.
To start with, she opens the package from Oh Chul-Young which happens to be his confession. He reveals that he left prison one night in 2017 when he heard his Mother died. He received 24 hours leave, where he killed Do-Ki's Mother. When he returned, he learned Kyu-Jung was being blamed for what he did.
This immediately brings Sung-Chul across to prison, where he meets Chul-Young and learns from his own mouth that he was the one responsible. His deception and lies have essentially been the catalyst for the spiraling revenge and anger both Do-Ki and Sung-Chul have experienced over the season.
Despite the Rainbow Taxi firm hanging up their revenge coats, a call comes in regarding Oh Chul-Young. It's Kyu-Jung, the guy who took the blame for his murders. He reaffirms how the law has failed him. Sung-Chul initially refuses to allow this case, prompting Do-Ki to take it on himself. This is personal, and eventually Sung-Chul caves and allows it as a final job.
Kyu-Jung was forced to take the brunt of punishment's for Chul-Young's crimes. He was beaten by police and then forced to live as an ex-con. After 20 years, and with Chul-Young confessing to everything, the law completed failed him in this instance and ruined his life. He wants an apology from Chul-Young, and given he has nothing else to lose, is prepared to be branded a criminal again to make this happen.
Back in the police station, Chul-Young's cruel ways are made worse when he admits to confessing the final words Do-Ki's mother uttered before she died. This brings Ha-Na to see Do-Ki, admitting that Chul-Young is the real criminal behind his Mother's death. He confirms her final words, and admits that he changed his methods for her. She lied and claimed Do-Ki's friends would be coming too, prompting him to scarper before finishing the job.
An enraged Do-Ki is overcome with emotion but he's not alone. Hyun-Soo, the child we saw from the start of the episode, happens to be Chul-Young's son and he's actually working as a prison guard.