Gook Young-soo is the founder and driving force behind the Criminal Behavior Analysis unit, a veteran who believes profiling can transform how investigations are run. Pragmatic and persistent, he spends as much energy defending the team from skeptical superiors and budget pressures as he does on the cases themselves. He recognizes Song Ha-young's talent early and works to give the younger analyst room to develop.
Throughout the season, Gook serves as the unit's institutional shield, absorbing criticism from a police culture that views behavioral analysis with suspicion. His leadership style is steady and protective, and his faith in the discipline gives the team the cover it needs to prove itself case by case.
Gook's journey mirrors the broader struggle of the series: the fight to establish profiling as a respected, permanent part of investigative work. By the end he stands as the figure who made the unit possible, a mentor whose conviction outlasts the early doubts of his peers.
Gook Young-soo is one of the central figures in Through the Darkness, a crime/drama/procedural/korean/thriller series that aired on SBS from 2022. Within the narrative of Through the Darkness, Gook Young-soo serves as a pivotal character whose decisions and relationships drive key story arcs throughout Season 1 (2022). The character's journey has been central to many of the show's most memorable and discussed moments.
Portrayed by Jin Sun-kyu, Gook Young-soo has become one of the most recognizable characters in modern television. Jin Sun-kyu's performance brings nuance and depth to the role, creating a character that resonates with audiences on both intellectual and emotional levels. Jin Sun-kyu's work has been recognized with 1 major award, reflecting the critical acclaim their portrayal has received.
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? Frequently Asked Questions
Gook Young-soo is played by Jin Sun-kyu, who portrays the founder of the Criminal Behavior Analysis unit and Song Ha-young's mentor.
He is the unit's founder and protector, championing criminal behavior analysis to skeptical superiors and giving the team the institutional support it needs to operate.
