Twenty years ago, "Locust," the world's top-ranked killer, vanished from the underworld to enter the Gu family as their butler, Ian Chen, in memory of his deceased lover, Liana Gu. Two decades later, Liana's brother inherits the family and has a daughter, Valerie Gu. Valerie secretly admires the extraordinarily capable butler. However, at a banquet, she catches the eye of Mason Qin, heir to the Qin family. Since the death of his beloved Nina Su, Mason has become unhinged, obsessively seeking look-alikes of Nina as replacements—girls who invariably end up dead. Because Valerie bears a striking resemblance to Nina, she becomes the target of Mason's twisted obsession. He threatens to destroy the Gu family if she refuses him. To protect them, Ian must utilize his brilliant intellect and formidable skills to wage war against the Qins.
