Goddess of Mercy (2003)

Yang Rui falls in love for the cleaning woman who works in a taekwando gym, only to later discover she's an undercover cop named An Xin. An is in hiding from drug smugglers who have a score to settle with her - a raid she led resulted in the death of one of the smuggler's parents. To complicate matters further, An was previously romantically involved with the smuggler whose parents were killed.