The story is about Hong Kong in the 1970s under British colonial rule, where corruption was rampant, where drug lords Kun and Hao were making a lot of money. Rose's father is killed by Kun for seizing drugs from him and refusing to compromise. Rose is sent to Taiwan by her uncle for refuge and grows up with the ambition to take revenge and bring Kun and other drug lords to justice, so as to return justice and clarity to society. Rose joins the Independent Commission Against Corruption (ICAC) and works with Interpol, lurking undercover with the drug lord Hao to get information. However, as Rose and Hao become better acquainted, there is a love affair between them that should happen is budding. On the one hand, she is avenging her father's death by bringing the drug lord to justice, and on the other hand, she is renewing the emotions of her childhood bond.