Mia, a medical student, saves Victor, a shot gang godfather, on a rainy night, leaving behind a snake-shaped lighter as a token. When her younger brother is kidnapped by the rival Viper Gang, Mia is forced to infiltrate Victor's manor as an undercover agent, seeking an opportunity to steal the vault key. Victor, who is already aware of her undercover identity, nevertheless falls deeply for her. Mia agonizingly struggles between her family loyalty and her growing feelings, until her brother is tragically killed. Facing reality, Mia lets go of her obsession and sheds her weakness, fighting alongside Victor to eliminate rival forces and personally exact her revenge. The formerly coerced undercover girl transforms into an independent and capable gang matriarch, spending her life with Victor.
