Good Boy Gone Bad follows Choi Yeonjun, the seemingly perfect son in the small town of Ravendale, whose sudden disappearance unravels a dark secret. Detective Park Sunmi discovers that Yeonjun has become involved with a dangerous group, The Collective, seeking power and escape from his perfect life. As Sunmi uncovers the truth, she learns that Yeonjun willingly betrayed everything he once valued. The story explores themes of identity, betrayal, the consequences of choices, and the possibility of redemption. Yeonjun's transformation from the "good boy" to someone lost in darkness forces Sunmi to confront whether he can ever return from the path he's chosen.