Hitman Blues.

Ting Sau-Ling (Jacqueline Ng) is kidnapped by a gang in Shenzhen but she's rescued by Lau Koon (Robert Mak Tak-Law). The two get to know each other--in order to survive Lau Koon resolutely sneaks into Hong Kong to kill the gang.Ting Kwok-Bo (Lau Dan), gang leader and acquaintance of Lau Koon, pleads to him and sends May (Isabel Leung Pooi-Woo) to be his lover. Tensions rise as the love triangle between Sau-Ling, Lau Koon, and May is complicated by the conspiracies of the gangs of Hong Kong.