Tae Soo goes home while working on a case to celebrate his daughter's birthday; he is called to a police substation to pick up his daughter; Tae Soo realises that Ha Bin could be involved in a murder case and starts doubting her.

Tae Soo wants to trust his daughter however every piece of evidence he comes across reveals traces of Ha Bin; during his investigation, Dae Hong discovers that Tae Soo is involved in this case.

Jeong Hwan and Yong Soo visit Ha Bin at her place to interrogate her; Tae Soo goes around trying to check Ha Bin's alibi; Ha Bin suggests to Tae Soo that they move, but Tae Soo insists on staying until he catches the real culprit.

A chilling discovery unfolds as a seemingly innocent keyring from Ha Bin reveals the possibility of a serial murder case. Tae Soo grows increasingly anxious, sensing that Young Min and Ha Bin are hiding something crucial. Just as the tension rises, the police arrive at Tae Soo\u2019s home once again, intensifying the fear of what secrets might be uncovered.

Tae Soo gets a call from his wife; Joon Tae becomes increasingly apprehensive as the investigation progresses. Ha Bin, who believes her mother is a murderer, begins to dig deeper into her mother's past as an unidentified man follows her from behind.

A man who claims to be Song Min Ah's dad appears before Ha Bin; Ha Bin learns from the man that Tae Soo helped Young Min escape from the police; the police raid Young Min's place and take all the kids for questioning.