Memorist (2020)

S1E11 A Deep Wound

Dong Baek and Sun Mi embark on another collaborative investigation to uncover the truth behind a hidden mass murder that took place two decades ago. As they delve into the case, they manage to uncover a crucial piece of information: the killer bears a significant scar on his right arm. Yet, amidst their discoveries, they fail to recognize a critical detail—there is someone close to them who has a strikingly similar scar.