In Episode 5 of Hunter with a Scalpel, Se-hyun discovers that the methods used in a current case mirror those of her father, Joe Hyan, a notorious serial killer she believed to be dead for 20 years. This discovery rekindles past trauma and fear, as she was the one who killed him. Realizing the danger is not over and that someone is mimicking her father's techniques, threatening her safety and reputation, Se-hyun decides to preempt the police investigation and hunt down the killer herself. The episode further develops the psychological tension and mystery of the series. Se-hyun also wants to erase her past and is hunting to do so before the police discover the truth.