After losing her only younger sister to an unidentified murderer, Hayeon is plunged into total despair when even the police fail to uncover a single lead. While chasing shadows on her own, she finds herself in mortal danger—only to be miraculously saved by Yuseong, an enigmatic man with striking blue heterochromia. Yuseong acts as though he already knows the killer's true identity, coldly warning Hayeon to abandon her quest for vengeance. Enraged by his callous attitude yet desperate for any shred of hope to catch the culprit, Hayeon tails him all the way back to his private quarters. There, she is confronted by the shocking truth: Yuseong's entire body is covered in countless horrific scars. As her sole remaining hope for justice, what dark secrets is this mysterious man hiding? Backed into a corner, Hayeon lays her life on the line with a reckless ultimatum: "Does it hurt you that much when someone dies because of you? If you won't help me, I'll kill myself right here in front of your eyes."