When Andy Lau was a child, double agent Ray Liu (Paul Chu) murdered his parents. Now, the grown-up Andy (Andy Lau Tak-Wah) is going after Ray in this action thriller from Hong Kong auteur Ringo Lam. After a failed attempt on Ray's life, Andy begins gathering criminal evidence on him for the CIA. When Andy begins to fall for Ray's daughter, however, he finds himself torn between fulfilling his vow and hurting the woman he loves.